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Knitting

Cooper Hewitt, Smithsonian Design Museum
Pattern with motif of enlarged stockinette knitting stitch diagram; color scheme of brown on cream ground.

Robertson Steam Engine Indicator

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The James L. Robertson & Sons company of New York, NY, manufactured this steam indicator set about 1906. The indicator is based on a design patented by Joseph W. Thompson (Patent No. 167,364, August 31, 1875) which made improvements in the mechanisms driving the recording stylus thus allowing improved measurements of higher speed steam engines. The design also includes elements from another patent by Mr. Robertson (No. 815,038, Mar 13, 1906). It dealt with the reduction wheel mechanism below the recording drum and specifically to the regulation of cord tension to improve accuracy. The reduction mechanism allowed for measuring engines with varying piston throw lengths. This indicator set includes the indicator itself; extra springs of varying stiffness for different steam pressures; a reducing wheel to decrease the piston motion to that required by the indicator drum; with sized wooden pulleys for different piston stroke lengths; an extra indicator piston of small diameter for very high pressures; scales for measuring the area of the diagram; servicing tools; and extra blanks. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Robertson-Thompson steam indicator represented over one hundred years of evolution and improvement of the devices. Its ability to make recordings for a wide range of engine speeds, pressures and piston stroke lengths was a significant improvement for many applications.

Robertson-Thompson Steam Engine Indicator - ca 1900

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The James L. Robertson & Sons of New York, NY, manufactured this steam indicator about 1900. The indicator is based on a design patented by Joseph W. Thompson which made improvements in the mechanisms driving the recording stylus thus allowing improved measurements of higher speed steam engines. The design also includes elements from another patent by Alpheus O. Lippincott and assigned to Robertson. It dealt with the reduction wheel mechanism below the recording drum. The reduction mechanism allowed for measuring engines with a variety of piston throw lengths.

This indicator set contains within the mahogany box the indicator itself; extra springs of varying stiffness for different steam pressures; a reducing wheel to decrease the piston motion to that required by the indicator drum; sized wooden pulleys for different piston stroke lengths; an extra indicator piston of small diameter for very high pressures; a planimeter for measuring the area of the diagram; servicing tools; and extra blanks. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed.

Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines. Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Robertson-Thompson steam indicator represented over one hundred years of evolution and improvement of the devices. Its ability to make recordings for a wide range of engine speeds, pressures and piston stroke lengths was a significant improvement for many applications.

Richards Steam Engine Indicator, ca 1864

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. This indicator was designed and patented (U.S. Patent No. 37980) by C.B. Richards of Hartford, CT in 1863. This particular unit was manufactured by Elliott Brothers of London, England. The American Steam Gauge Co. of Boston, MA also manufactured this type of indicator. Made of brass, it consists of a cylinder and piston and a separate drum mounted on a parallel axis holding the recording paper. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine. The Richards Indicator was a significant improvement over the then standard McNaught Indicator which was not fully satisfactory for measurements of high speed steam engines. Richards' patent for his indicator makes note of the lightness and short stroke of the indicator's piston. This reduced the inertia of the moving parts of the unit and enabled its use on high speed engines. Richards’ patent also added a system of levers to the recording stylus in order to multiply the piston range by a factor of four while still producing a straight vertical motion proportional to the piston extension. This enabled a large and legible diagram to be traced on the drum even with the reduced piston range. The levers and pencil are made from lightweight materials to again reduce inertia.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Richards steam indicator represented over one hundred years of evolution and improvement of the devices. Its ability to make recordings on high speed steam engines was a significant improvement for many applications.

Planimeter, Parallel Bar Type

National Museum of American History
This instrument consists of 12 flat parallel metal rods screwed at each end to somewhat wider parallel rods. The rods are equally spaced, except for the first and last, which are only half as far apart as the others. The device was designed for locating ordinates on a steam-engine indicator diagram that should be measured and multiplied by the length of the diagram to give a rough estimate of the area under the curve. This object was owned by the renowned American designer of steam engines, Erasmus Darwin Leavitt Jr. (1836–1916), and donated by his granddaughter, Margaret van D. Rice. Reference: N. Hawkins, Hawkins' Indicator Catechism (New York: Theo. Audel & Co., 1903), 107–110.

Alfred Vail's Drawing of Many Circuits with One Battery

Smithsonian Archives - History Div
Alfred Vail was a key partner to American inventor Samuel Morse and is credited with designing the machine and alpha code used in the creation of the electromagnetic telegraph.

For other materials relevant to Vail's work, see Negative Numbers SIA2011-0824 to SIA2011-0826, and SIA2011-0828 to SIA2011-0830. For letters between Vail, Morse, and first Smithsonian Secretary Joseph Henry, see Negative Numbers SIA2011-0814 to SIA2011-0823.

This page is from Alfred Vail's scientific notebook, and it shows a diagram of one of his experiments. The diagram shows an arrangement of many circuits with only one battery and one wire for a common circuit. This experiment was designed for when different letters are desired in succession.

Hopkinson Steam Engine Indicator

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The J. Hopkinson & Company of Huddersfield, England manufactured this steam engine indicator ca 1855. Made of brass, it consists of an internal cylinder and piston which is surrounded by a concentric brass drum holding the recording paper. The piston causes the stylus to rise and fall with pressure changes thereby directly recording the indicator’s pressure-volume diagram output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do.

McNaught Steam Engine Indicator - ca 1842

National Museum of American History
An engine indicator is an instrument for graphically recording the cylinder pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. This type of indicator was invented by John McNaught of Glasgow, Scotland around 1825/1830. This particular unit was manufactured by Novelty Iron Works of New York around 1842.

The McNaught indicator was a significant improvement over the original Watt indicator which made steam-pressure diagrams on a flat piece of recording paper. The piston of the engine under test moved the paper horizontally, and the indicator’s piston moved the paper vertically. McNaught’s improvement was the introduction of an oscillating cylinder which held the recording paper. Made of brass, it consists of a cylinder and piston with internal spring and a separate recording drum. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed.

Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines. Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do.

Indicator with Reducing Wheel

National Museum of American History
This indicator, designed to meet the requirements of early 20th century high-speed engines, employs the lightest construction consistent with strength and accuracy. It is equipped with a reducing wheel, which is a self-contained device capable of reducing engine strokes of 14 to 72 inches to the proper stroke of the paper drum.

The cylinder of this indicator is supported so that its lower end is free and its longitudinal expansion or contraction is unimpeded. The annular space between the cylinder and the casing is designed to serve as a steam jacket. The piston is an extremely thin steel shell with shallow channels on its outer surface to provide steam packing and moisture lubrication. The piston rod is hollow and is connected to the pencil mechanism by means of a swivel head that can be screwed in or out of the rod to adjust the position of the diagram on the paper. The pencil mechanism is kinematically a pantograph that theoretically gives the pencil point a movement exactly parallel to the piston and the amount of the movement of the piston is multiplied six times at the pencil point. The design of the piston spring is peculiar to this indicator. It is made of a single piece of spring steel wire wound from the middle into a double coil, the ends of which are screwed into a metal head drilled helically to receive the spring.

The exact strength of spring is obtained by screwing the spring into the head more or less, when they are firmly fixed. The foot of the spring is a small steel bead firmly pinned to the straight portion of wire at the bottom of the spring. This takes the place of the heavier brass foot used in earlier indicators.*

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

*Reference:

This description comes from the 1939 Catalog of the Mechanical Collections of the Division of Engineering United States Museum Bulletin 173 by Frank A. Taylor.

J. W. Thompson Steam Engine Indicator

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The American Steam Gauge Company of Boston, MA manufactured this indicator. It is an internal spring indicator based on a design by Joseph W. Thompson which he patented on August 31, 1875 . This design reduced the size and weight of the recording mechanism in order to allow more accurate measurements of high speed steam engines. The indicator consists of a brass cylinder with internal spring and piston connected to a recording stylus and a recording drum. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Thompson steam indicator set represented over one hundred years of evolution and improvement of the devices. Its ability to make measurements on a high speed steam engine was a significant improvement for many applications.

Thompson Matched Pair, Steam Engine Indicators

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The American Steam Gauge Company of Boston, MA manufactured these indicators. They are a matched pair of internal spring indicators based on a design by Joseph W. Thompson which he patented on August 31, 1875 . This design reduced the size and weight of the recording mechanism in order to allow more accurate measurements of high speed steam engines. Each of the indicators consists of a brass cylinder with internal spring and piston connected to a recording stylus and a recording drum. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Thompson steam indicator set represented over one hundred years of evolution and improvement of the devices. Its ability to make simultaneous recordings of two cylinders on a high speed steam engine was a significant improvement for many applications.

Sketch of Circuits Using One Battery

Smithsonian Archives - History Div
Alfred Vail was a key partner to American inventor Samuel Morse and is credited with designing the machine and alpha code used in the creation of the electromagnetic telegraph.

For other materials relevant to Vail's work, see Negative Numbers SIA2011-0824 to SIA2011-0829. For letters between Vail, Morse, and first Smithsonian Secretary Joseph Henry, see Negative Numbers SIA2011-0814 to SIA2011-0823.

Alfred Vail's sketch is a diagram of one of his experiments. This diagram shows Vail's attempt to connect multiple circuits with one battery and one wire. At the bottom of the letter Samuel Morse has written: "This is Mr. Vail's arrangement. August 16th 1844."

Moyens Facille et Efficace pour Diriger les Globes Aerostatiques. Executeé en petit par françois, Joseph, Plancq, Demeurant à Lille de 3 7bre 1785...

National Air and Space Museum
Uncolored etching of a diagram for a balloon. The balloon has large fins (idenitified as fabric wings-ailes de tafettas) at the top of the balloon and below the basket. There is also a large paddle attached to the basket. Letters on the diagram correspond to the key in the top left corner. Key and descriptions are in French. The design was the basis for a model constructed by Francois-Joseph Plancq, and presented to a magristrate of Lille on November 16, 1785.

Ross Surface Form #16, Dissection Illustrating the Pythagorean Theorem

National Museum of American History
This is the sixteenth in a series of models of plane figures (surface forms) designed by William Wallace Ross, a school superintendent and mathematics teacher in Fremont, Ohio. It illustrates the Pythagorean theorem for a right triangle of sides of length 3, 4, and 5. The unpainted wooden object consists of a central right angled triangle with a square attached to each side. The smallest square is undivided. A paper sticker on it has a mark that reads: Right Angled Triangle with Attached (/) Squares 3x4x5. The next largest square is divided into four pieces and has a paper sticker with a diagram on it attached to one piece. The largest square is divided into three unequal pieces, with a paper sticker with a diagram on it attached to one piece. The backs of the three squares are divided into square grids. Rearranging the four pieces adjacent to the medium-sized square around the small square gives a square equal in area to the largest square. One also can rearrange the pieces of the large square to form two adjacent squares, each equal in area to one of the smaller squares. This illustration of the Pythagorean theorem is associated with the English mathematician Henry Perigal. For further information about Ross models, including references, see 1985.0112.191. Reference: Henry Perigal, “On geometric dissections and transformations, The Messenger of Mathematics, 1, 1874, pp. 103-106.

In Three Years the Freedom Tower Will no Longer be America's Tallest Building

Smithsonian Magazine

It seems like only yesterday that the Freedom Tower at One World Trade Center in New York beat Chicago for the hemisphere’s tallest building. Now, CityLab’s Kriston Capps reports that there’s a new tallest tower coming to town: the Nordstrom Tower, which will rise to a height of 1,795 feet and a title of the Western Hemisphere’s tallest building.

Capps reports on new diagrams for 217 West 57th Street  show the tower smashing height records. These plans have long been shrouded in secrecy, Nikolai Fedak reports for New York Yimby. Initially, the tower was supposed to lose to One World Trade Center by one foot. Now, newly-released drawings show a tower with 93 floors and a 265-foot parapet that beats out the Freedom Tower’s spire by 19 feet. Fedak writes that concrete is already being poured for the residential tower, which will open sometime in 2018.

Despite New York’s play for the Western Hemisphere’s tallest skyline, it pales in comparison with the Eastern Hemisphere. Dubai’s Burj Khalifa, which contains offices, a hotel, and plush apartments, is 2,716 feet tall. Baffled by cities’ skyline wars? Don’t worry — organizations like the Council on Tall Buildings and Urban Habitat, which keeps a database of tall urban buildings and even gives out annual tallest building awards, keep track so you don’t have to.

The Aerostat,--Worked by Manual Power--Invented by W. Miller, M.R.C.S.

National Air and Space Museum
Colored lithograph of the "Aerostat" flying machine aloft over a field with a river and city in the background. A diagram of the machine is below the scene with a scale and captions. This hand-operated ornithopter was designed, but apparently neither built nor tested by W. Miller Text to the right of the diagram has a more detailed description of the machine and how it is operated. After a drawing by J. Absolon.

'London. Published for the Proprietor by Ackermann & Co. 96, Strand; T. McLean, 26, Haymarket; J. Cross, 18, Holborn; and R. Lambe, 96, Gracechurch Street; 22nd April 1843. J. Absolon delt. C.F. Cheffins Lithogr.'

Integrating Steam Engine Indicator

National Museum of American History
This device is designed to integrate the area under the indicator diagram and will total the work for several strokes of the piston. A small metal cylinder about one inch by three-quarters is geared to a counter. The cylinder turns about its horizontal axis, and a small metal disc bears against the cylinder. The plane of the disc coincides with the axis of the cylinder and is turned by the motion of the indicator piston. The motion of the engine piston moves the cylinder horizontally. This combined action results in the rotation of the cylinder. The increment to rotation is proportional to the angle of the disc.

The manufacturer of this indicator is unknown. The spring is missing, although Thompson indicator springs will fit it. Similar instruments are described in William Robinson’s book Gas and Petroleum Engines: A Manual for Students and Engineers (Spon & Chamberlain, New York: 1902).

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Richards Steam Engine Indicator - ca 1863

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. This indicator was designed and patented by C.B. Richards of Hartford, CT in 1863 . Units of this design were manufactured by the American Steam Gauge Co. of Boston, MA and the Elliott Brothers of London, England.

Made of brass, it consists of a cylinder and piston and a separate drum mounted on a parallel axis holding the recording paper. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The Richards Indicator was a significant improvement over the then standard McNaught Indicator which was not fully satisfactory for measurements of high speed steam engines. Richards' patent for his indicator makes note of the lightness and short stroke of the indicator's piston. This reduced the inertia of the moving parts of the unit and enabled its use on high speed engines. Richards’ patent also added the system of levers to the recording stylus in order to multiply the piston range by a factor of four while still producing a straight vertical motion proportional to the piston extension. This enabled a large and legible diagram to be traced on the drum even with the reduced piston range. The levers and pencil are made from lightweight materials to again reduce inertia.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed.

Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines. Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Richards steam indicator represented over one hundred years of evolution and improvement of the devices. Its ability to make recordings on high speed steam engines was a significant improvement for many applications.

Sketch of stretched shell housing

Archives of American Art
1 sketch : ink ; 30 x 20 cm,

Ink sketch of design for stretched shell housing, with diagrams and inscriptions.

Ashcroft-Tabor Steam Engine Indicator

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. The Ashcroft Manufacturing Company of Bridgeport, CT manufactured this steam indicator. It is marked as having been patented December 10, 1878 and is stamped with Number 2078. The patent, Number 210,643 was granted to Harris Tabor of Corning, NY who later sold it to Ashcroft Manufacturing . The primary claim of the patent was improved measurement of high speed steam engines due to reduction of the number and weight of moving parts. Enclosed in a wooden case, it consists of a plated brass cylinder and piston with internal interchangeable spring and attached stylus mechanism, and the drum which holds the recording paper. Also included are various tools and parts including two attachment valves, four piston springs of various thickness, wrenches and rulers. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Ashcroft-Tabor steam indicator represented nearly one hundred years of evolution and improvement of the devices. Its ability to make recordings on high speed steam engines was a significant improvement for many applications.

Watt Steam Engine Indicator (Replica, 1927)

National Museum of American History
An engine indicator is an instrument for graphically recording the cylinder pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. This is a replica of the original steam indicator invented in the late 18th Century by James Watt of Scotland. This was the first device intended to measure the varying pressures within a stem engine’s cylinder as it was working.

Originally consisting of only the brass cylinder and piston, Watt’s assistant (John Southern) made the important improvement of the recording tablet and pencil that resulted in the ability to make a lasting recording of a complete cycle of the engine under measurement. The piston of the engine moved the tablet horizontally via an attached cord, and the indicator’s piston moved the pencil vertically. A weight attached to the tablet via a pulley caused the tablet to move back horizontally as the engine’s piston returned to its original position. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of this steam indicator in the late 1790s by James Watt had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed.

Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines. Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do.

Crosby Pair of Steam Engine Indicators, ca 1930

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. Manufactured by Crosby Steam Gage & Valve Co. of Boston, Massachusetts, these steam engine indicators are enclosed in a wooden case. Each consists of a steel piston; an interchangeable external, helical wound spring; a large single recording drum with a spiral spring; and a brass stylus. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine. These indicators enabled simultaneous measurement of both ends of a cylinder.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. These Crosby steam indicators represented over one hundred years of evolution and improvement of the devices.

Lippincot Steam Engine Indicator

National Museum of American History
An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine. Manufactured by Lippincott Steam Specialty and Supply Company of Newark, NJ, this steam engine indicator is enclosed in a mahogany case. It consists of a steel piston; an external spring, which can be changed; a large single recording drum with a spiral spring; a reduction wheel mechanism; and a brass stylus. Included within the case are miscellaneous accessories including: extra springs, adaptor valves, and small tools. The piston causes the stylus to rise and fall with pressure changes in the engine under measurement thereby directly recording the indicator’s output on the paper. Around the drum’s base is wound a cord that is attached to the connecting rod of the piston on the steam engine being measured. This causes the drum to rotate as the engine’s piston moves. An internal coil spring causes the cord to retract and the drum to counter rotate back to its original position as the connecting rod returns. The result is a steam pressure-volume diagram which is used to measure the efficiency and other attributes of the steam engine.

The introduction of the steam indicator in the late 1790s and early 1800s by James Watt and others had a great impact on the understanding of how the steam behaved inside the engine's cylinder and thereby enabled much more exacting and sophisticated designs. The devices also changed how the economics and efficiency of steam engines were portrayed and marketed. They helped the prospective owner of a machine better understand how much his fuel costs would be for a given amount of work performed. Measurement of fuel consumed and work delivered by the engine was begun by Watt, who in part justified the selling price of his engines on the amount of fuel cost the purchaser might save compared to an alternate engine. In the early days of steam power, the method to compare engine performance was based on a concept termed the engine’s “duty”. It originally was calculated as the number of pounds of water raised one foot high per one bushel of coal consumed. The duty method was open to criticism due to its inability to take into consideration finer points of efficiency in real world applications of engines . Accurate determination of fuel used in relation to work performed has been fundamental to the design and improvement of all steam-driven prime movers ever since Watt’s time. And, the steam indicators’ key contribution was the accurate measurements of performance while the engine was actually doing the work it was designed to do. This Lippincott steam indicator represented over one hundred years of evolution and improvement of the devices.

Shlarbaum’s Patent Model of an Oscillating Steam Engine– ca 1863

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 39,756 issued to Hermann Shlarbaum of New York, New York on September 1, 1863. The patent was for an improvement in oscillating steam engines. An oscillating steam engine differs from a standard engine in that the steam cylinder is pivoted on the engine frame and oscillates up and down about the pivot as its connecting rod operates the crankshaft of the engine. In a standard engine, the cylinder is fixed in orientation, and the piston rod moves fore and aft within a crosshead which allows the connecting rod to pivot independently as the crankshaft revolves.

Shlarbaum did not claim his overall design as new. Others had patented very similar designs. His claim was for the unique design of the steam and exhaust valves for the engine. The claimed benefits of this design included simplicity and economy of manufacture, operation and maintenance. The inventor also claimed that his design avoided having lubricating oil in the pivot being overheated by high pressure steam. A search of available literature did not reveal any commercial use of the patent.

The patent model is constructed of cast iron and brass. All of the key elements of the patent are illustrated by the model to include the valve mechanism. A full description of the workings of the engine and diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website, /www.uspto.gov.
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