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Numbers Don’t Lie: The CD Really Is Dead

Smithsonian Magazine

As streaming music gains popularity, record companies have insisted it’s not threatening their sales. But newly released statistics suggest that streaming music may be killing a format instead. For the first time ever, streaming revenues have surpassed those made by compact discs.

A new report from the Recording Industry Association of America shows that streaming outlets generated $1.87 billion in 2014—while CD sales fell to $1.85 billion. Streaming music’s edge is slight but significant: it now accounts for 27 percent of the industry’s total revenues. And while permanent downloads still dominate the digital music market (with $2.58 billion in revenues, they bring in about 38 percent more than streaming services), streaming is catching up quickly.

With digital music now capturing 65 percent of the market’s revenues, it’s easy to predict the demise of all physical formats. But there is one dark horse in the game. The RIAA’s report also showed that vinyl sales continue to rise (revenues are up 50 percent since 2013). LPs have staged what the Wall Street Journal calls “the biggest music comeback of 2014,” and the format is making gains with the same under-35 demographic that’s fueling streaming music. 

The humble CD isn’t the only format that’s being edged out by a changing music market, either. Streaming music is threatening another mainstay: the car radio. The New York Post reports that terrestrial radio is being edged out by streaming services like Sirius XM and Pandora—and by 2018, more than 60 percent of new vehicles in the United States will come equipped with the technology it takes to stream on the go.

Magnetometer

National Museum of American History
This theodolite magnetometer is based on the design that the U.S. Coast and Geodetic Survey developed in 1892-1893. It is similar in many ways to the instrument that the Survey had been using since the early 1880s, but with several new features. One is the octagonal shape of the collimating magnets. Another is the black velvet screen that connects the telescope with the suspension box: this cuts off stray light and eliminates the problems that had been caused by the glass window in the earlier form. It is marked "FAUTH & CO. WASHN D.C. 941" and "T.M.C.I. 1." The serial number suggests that it was made around 1895. This instrument belonged to the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. Internal records indicate that D.T.M. purchased it from Kolesch & Co. in New York in 1906 (for $175), sent it to Bausch, Lomb, Saegmuller Co. for repairs (another $120), and kept it in service until 1919. Ref: Edwin Smith, "Notes on Some Instruments Recently Made in the Instrument Division of the Coast and Geodetic Survey Office," Annual Report of the Superintendent of the U.S. Coast and Geodetic Survey for 1894, Appendix No. 8.

Giant boid snake from the Palaeocene neotropics reveals hotter past equatorial temperatures

Smithsonian Libraries
The largest extant snakes live in the tropics of South America and southeast Asia1, 2, 3 where high temperatures facilitate the evolution of large body sizes among air-breathing animals whose body temperatures are dependant on ambient environmental temperatures (poikilothermy)4, 5. Very little is known about ancient tropical terrestrial ecosystems, limiting our understanding of the evolution of giant snakes and their relationship to climate in the past. Here we describe a boid snake from the oldest known neotropical rainforest fauna from the Cerrejón Formation (58–60 Myr ago) in northeastern Colombia. We estimate a body length of 13 m and a mass of 1,135 kg, making it the largest known snake6, 7, 8, 9. The maximum size of poikilothermic animals at a given temperature is limited by metabolic rate4, and a snake of this size would require a minimum mean annual temperature of 30–34 °C to survive. This estimate is consistent with hypotheses of hot Palaeocene neotropics with high concentrations of atmospheric CO2 based on climate models10. Comparison of palaeotemperature estimates from the equator to those from South American mid-latitudes indicates a relatively steep temperature gradient during the early Palaeogene greenhouse, similar to that of today. Depositional environments and faunal composition of the Cerrejón Formation indicate an anaconda-like ecology for the giant snake, and an earliest Cenozoic origin of neotropical vertebrate faunas.

The Major-Element Composition of Mercury’s Surface from MESSENGER X-ray Spectrometry

Smithsonian Libraries
X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet’s surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observation, together with a low surface Fe abundance, supports the view that Mercury formed from highly reduced precursor materials, perhaps akin to enstatite chondrite meteorites or anhydrous cometary dust particles. Low Fe and Ti abundances do not support the proposal that opaque oxides of these elements contribute substantially to Mercury’s low and variable surface reflectance.

Spectroscope

National Museum of American History
This is a direct-vision spectroscope with a seven-part prism. The three sections (collimator, prism train and telescope) screw together to form an instrument 18 inches long overall. The “John Browning / London” inscription refers to John Browning (ca. 1831-1925), the first important English spectroscope maker. The “Alex. R. Newman” inscription on the top of the mahogany box has not been identified. The “1173” incised on the inside of the box may be a serial number. Browning introduced the seven prism form in 1869. A reliable text published in 1872 stated that this instrument “commends itself by the excellence of its performance, the facility of its use, the smallness of its dimension, the purity of colour, and its low price.” Ref: John Browning, How to Work with the Spectroscope (London / New York, 1878). H. Schellen, Spectrum Analysis in its Application to Terrestrial Substances, and the Physical Constitution of the Heavenly Bodies (London, 1872), p. 119.

Priming depletes soil carbon and releases nitrogen in a scrub-oak ecosystem exposed to elevated CO2

Smithsonian Libraries
Elevated atmospheric CO2 tends to stimulate plant productivity, which could either stimulate or suppress the processing of soil carbon, thereby feeding back to atmospheric CO2 concentrations. We employed an acid-hydrolysis-incubation method and a net nitrogen-mineralization assay to assess stability of soil carbon pools and short-term nitrogen dynamics in a Florida scrub-oak ecosystem after six years of exposure to elevated CO2. We found that soil carbon concentration in the slow pool was 27% lower in elevated than ambient CO2 plots at 0-10 cm depth. The difference in carbon mass was equivalent to roughly one-third of the increase in plant biomass that occurred in the same experiment. These results concur with previous reports from this ecosystem that elevated CO2 stimulates microbial degradation of relatively stable soil organic carbon pools. Accordingly, elevated CO2 increased net N mineralization in the 10-30 cm depth, which may increase N availability, thereby allowing for continued stimulation of plant productivity by elevated CO2. Our findings suggest that soil texture and climate may explain the differential response of soil carbon among various long-term, field-based CO2 studies. Increased mineralization of stable soil organic carbon by a CO2-induced priming effect may diminish the terrestrial carbon sink globally.

Cary 12-Inch Celestial Globe

National Museum of American History
The cartouche reads “CARY’S / NEW / CELESTIAL GLOBE, / are correctly laid down upwards of 3500 stars / selected from the most accurate observations / and calculated for the year 1800. / With the extent of each constellation precisely defined / By Mr. GILPIN of the ROYAL SOCIETY. / Made and Sold by J. & W. CARY. / Strand London Jan. 1 1816.” The globe is held on a wooden pedestal with three curved legs. It has a wooden horizon circle and a brass meridian. John Cary was a globe maker in London who began in business in 1791. For this globe (and a few other things) he worked with his brother William. George Gilpin worked as an assistant at the Royal Observatory at Greenwich for a couple of years, and as the clerk of the Royal Society of London from 1785 until his death in 1810. Cary introduced his new 12-inch celestial globe and the terrestrial mate in 1798. This example is dated 1816. Ref: Herbert George Fordham, John Cary: Engraver, Map, Chart and Print-Seller and Globe-Maker, 1754 to 1835 (Cambridge, 1925)

An analysis of sinuous ridges in the southern Argyre Planitia, Mars using HiRISE and CTX images and MOLA data

Smithsonian Libraries
A suite of sinuous ridges with branching and braided morphologies forms an anastomosing network in southern Argyre Planitia, Mars. Several modes of origin have been proposed for the Argyre ridges. Imagery from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) aboard Mars Reconnaissance Orbiter (MRO) and Mars Orbiter Laser Altimeter (MOLA) topographic data sets from Mars Global Surveyor (MGS) are used to constrain processes involved in formation of the Argyre ridges. We find the characteristics of the ridges and associated layered deposits consistent with glaciofluvial-lacustrine processes and conclude that the ridges are most likely eskers. In particular, variations in ridge height appear to be related to the surrounding surface slope; ridge height increases with descending slopes and decreases with ascending slopes. This characteristic is observed in terrestrial eskers and is related to subice flow processes. The nature of some eroding beds in the ridges suggests induration. If the Argyre ridges are indeed eskers, the southern Argyre basin was once covered by the margin of a large, thick, stagnating or retreating ice deposit that extended for hundreds of kilometers or more. During ridge formation, water flowed on top, within, or beneath the ice deposit; the continuity and preservation of the ridges suggests that flow was primarily at the base of the ice. The dimensions (up to hundreds of meters tall and several kilometers wide), aspect ratio, and extent (hundreds of kilometers) of the ridges, as well as preliminary calculations of discharge, suggest that a significant amount of water was available.

Calibrating the End-Permian Mass Extinction

Smithsonian Libraries
The end-Permian mass extinction was the most severe biodiversity crisis in Earth history. To better constrain the timing, and ultimately the causes of this event, we collected a suite of geochronologic, isotopic, and biostratigraphic data on several well-preserved sedimentary sections in South China. High-precision U-Pb dating reveals that the extinction peak occurred just before 252.28 +/- 0.08 million years ago, after a decline of 2 per mil (parts per thousand) in delta(13)C over 90,000 years, and coincided with a delta(13)C excursion of -5 parts per thousand that is estimated to have lasted <= 20,000 years. The extinction interval was less than 200,000 years and synchronous in marine and terrestrial realms; associated charcoal-rich and soot-bearing layers indicate widespread wildfires on land. A massive release of thermogenic carbon dioxide and/or methane may have caused the catastrophic extinction.

Stable Carbon and Oxygen Isotope Spacing Between Bone and Tooth Collagen and Hydroxyapatite in Human Archaeological Remains

Smithsonian Libraries
Spacing between stable isotope values in bones and teeth is a valuable tool for examining dietary influences and diagenesis. This study examines carbon and oxygen isotope values from collagen and hydroxyapatite (structural carbonate and phosphate) in archaeological human bones and teeth to derive species-specific correlation equations and isotope spacing values. The ?13Ccollagen and ?13Cstructural carbonate in bone and dentin collagen show a strong correlation (R = 0.87, 0.90, respectively) with an average ?13Ccarb-coll spacing of 5.4?. The consistency of this isotope spacing with other large mammals and in humans with both low and high protein intake (as indicated by enriched ?15N values) suggests a similar allocation of protein-derived carbon and whole diet-derived carbon to collagen and structural carbonates, respectively, as other terrestrial mammals regardless of absolute meat intake. The ?18Ostructural carbonate and ?18Ophosphate show the strongest correlation in enamel (R = 0.65), weaker correlations in dentin (R = 0.59) and bone (R = 0.35), with an average ?18Ocarb-phos of 7.8?. This isotope spacing is slightly lower than previously reported for large mammals and limited available data for humans. The results potentially indicate species-specific fractionations and differing access to body water and blood-dissolved inorganic carbonates in the presence of collagen formation. The use of correlation between ?18Ostructural carbonate and ?18Ophosphate to determine diagenetic state is not recommended. The strength of this correlation observed in bones and teeth is variable and alternate indicators of diagenetic state (i.e. C:N ratios of collagen) provide more robust and independent evidence of isotope preservation despite presence/absence of a strong isotope correlation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Saxton Metallic Thermometer

National Museum of American History
Joseph Saxton, an accomplished scientist, inventor, and mechanician, joined the staff of the U.S. Coast Survey in 1844 at the request of the new Superintendent, Alexander Dallas Bache, and began developing instruments for measuring various terrestrial phenomena. Among the first was a metallic thermometer for use in deep water. Bache described this in 1848, saying that it proved “decidedly the most convenient” of the several forms tried. The thermometer coil was “like that of Breguet, only of much stouter material, and of two metals, silver and platinum, soldered together.” And the “plan of registering resembles that adopted by Jurgensen of Copenhagen, and by Montandon of Washington, in their metallic thermometers.” Several of Saxton’s thermometers were made in the Coast Survey’s instrument shop, and were still in use at the start of World War I. This example came to the Smithsonian in 1929. Here the thermometer is held in a brass cylinder that is encased in a hexagonal frame. The cap of the cylinder is marked “SAXTON’S / METALLIC THERMOMETER / 17.” The scale around the circumference of the thermometer extends from -40 to +174 degrees Fahrenheit; one of the two pointers registers the lowest temperature to which the thermometer was exposed. Ref: [A. D. Bache], Report of the superintendent of the coast survey, showing the progress of the work during the year ending November, 1848, p. 39. Bache, “Lecture on the Gulf Stream, prepared at the request of the American Association for the Advancement of Science,” Report of the Superintendent of the Coast Survey during the Year 1860, pp. 165-176, on 166.

Fire, hurricane and carbon dioxide: effects on net primary production of a subtropical woodland

Smithsonian Libraries
* Disturbance affects most terrestrial ecosystems and has the potential to shape their responses to chronic environmental change. * Scrub-oak vegetation regenerating from fire disturbance in subtropical Florida was exposed to experimentally elevated carbon dioxide (CO2) concentration (+350 ?l l-1) using open-top chambers for 11 yr, punctuated by hurricane disturbance in year 8. Here, we report the effects of elevated CO2 on aboveground and belowground net primary productivity (NPP) and nitrogen (N) cycling during this experiment. * The stimulation of NPP and N uptake by elevated CO2 peaked within 2 yr after disturbance by fire and hurricane, when soil nutrient availability was high. The stimulation subsequently declined and disappeared, coincident with low soil nutrient availability and with a CO2-induced reduction in the N concentration of oak stems. * These findings show that strong growth responses to elevated CO2 can be transient, are consistent with a progressively limited response to elevated CO2 interrupted by disturbance, and illustrate the importance of biogeochemical responses to extreme events in modulating ecosystem responses to global environmental change.

Key science questions from the second conference on early Mars: geologic, hydrologic, and climatic evolution and the implications for life

Smithsonian Libraries
In October 2004, more than 130 terrestrial and planetary scientists met in Jackson Hole, WY, to discuss early Mars. The first billion years of martian geologic history is of particular interest because it is a period during which the planet was most active, after which a less dynamic period ensued that extends to the present day. The early activity left a fascinating geological record, which we are only beginning to unravel through direct observation and modeling. In considering this time period, questions outnumber answers, and one of the purposes of the meeting was to gather some of the best experts in the field to consider the current state of knowledge, ascertain which questions remain to be addressed, and identify the most promising approaches to addressing those questions. The purpose of this report is to document that discussion. Throughout the planet's first billion years, planetary-scale processes-including differentiation, hydrodynamic escape, volcanism, large impacts, erosion, and sedimentation-rapidly modified the atmosphere and crust. How did these processes operate, and what were their rates and interdependencies? The early environment was also characterized by both abundant liquid water and plentiful sources of energy, two of the most important conditions considered necessary for the origin of life. Where and when did the most habitable environments occur? Did life actually occupy them, and if so, has life persisted on Mars to the present? Our understanding of early Mars is critical to understanding how the planet we see today came to be.

Monkeys Like Full Red Lips, Too

Smithsonian Magazine

A pair of red, glossy lips is a popular advertisement for sexiness, and this ideal has left its mark all over human culture: Applying a "cupid’s bow" was a key part of flapper attire in the 1920s, for example, and people’s thirst for lip color is strong enough that they have endured some strange and dangerous lipstick ingredients. But we aren’t the only species to find reddened lips alluring. 

Black-and-white snub-nosed monkeys enjoy a bit of natural lipstick, reports David Shultz for Science. The smaller primate’s twist on the phenomenon is that the red color also decorates the lips of males, and only the sexiest males get to wear the brightest colors.

Researchers hailing from China, the U.K, Australia and the U.S. describe how males of the large, endangered primate species have lips that redden as they age. Unlike the flashy plummage of male birds and bright colors of male fish, the monkey lip color isn’t just a way to attract females, the researchers write in Royal Society Open Science. Since older males have redder lips and bachelor males keep their lips pale, the "lipstick" might also serve as a way to enforce social hierarchy. 

"Paler lips could make bachelors appear less threatening, allowing the mating males to focus their aggression on other red-lipped competitors," Shultz writes. It’s also possible that the ladies prefer red-lipped mates, but the researchers’ data couldn’t offer a firm indication either way. Both mechanisms—sexual selection and male-male competition—could be at play. Lip color intensity was most intense during the peak of the mating season, the researchers note.

Other monkeys also redden in various part of their bodies, such as their faces, around their genitals and all over their skin. Some of these changes appear to be related to sexual availability and some in response to social order. At least it seems that for primates the world over, red is an exciting color.

A sustained +21 m sea-level highstand during MIS 11 (400 ka): direct fossil and sedimentary evidence from Bermuda

Smithsonian Libraries
A small, protected karstic feature exposed in a limestone quarry in Bermuda preserved abundant sedimentary and biogenic materials documenting a transgressive phase, still-stand, and regressive phase of a sea-level in excess of 21.3 m above present during Marine Isotope Stage (MIS) 11 (400 ka) as determined by U/Th dating and amino acid racemization. Cobbles and marine sediments deposited during the high-energy transgressive phase exhibit rim cements indicating a subsequent phreatic environment. This was succeeded stratigraphically by a still-stand deposition of fine calcareous lagoonal sediments containing bioclasts of red algae and benthic and planktonic foraminifera that was intensely burrowed by marine invertebrates, probably upogebiid shrimp, that could not be produced under any condition other than sustained marine submergence. Overlying this were pure carbonate beach sands of a low-energy regressive phase containing abundant remains of terrestrial and marine vertebrates and invertebrates. The considerable diversity of this fauna along with taphonomic evidence from seabird remains indicates deposition by high run-up waves over a minimum duration of months, if not years. The maximum duration has yet to be determined but probably did not exceed one or two thousand years. The most abundant snails in this fauna are two species indicative of brackish water and high-tide line showing that a Ghyben-Herzberg lens must have existed at > + 20 m. The nature of these sediments and fossil accumulation is incompatible with tsunami deposition and, given the absence of evidence for tectonic uplift of the Bermuda pedestal or platform, provide proof that sea-level during MIS 11 exceeded +20 m, a fact that has widespread ramifications for geologists, biogeographers, and human demographics along the world's coastlines.

Callipterid peltasperms of the Dunkard Group, Central Appalachian Basin

Smithsonian Libraries
Abstract The Dunkard Group is the youngest late Paleozoic rock unit in the Central Appalachian Basin. Its age, however, remains controversial. In its southern and western two-thirds the Dunkard is comprised largely of red beds, sandstone and siltstone channel deposits and paleosols. In its thickest, most northerly exposures, in southwestern Pennsylvania, northern West Virginia, and east-central Ohio, much of the lower part of the unit is composed of coals, non-marine limestones and gray, often calcareous, paleosols. Age dating is confounded by the non-marine nature of the deposit and by the lack of dateable volcanic ash beds. Dunkard fossils include plants, vertebrates, and both aquatic and terrestrial invertebrates. Most of the fossil groups point to an age very close to, if not including, the Pennsylvanian-Permian boundary, though the exact position of that boundary is uncertain. Callipterids make their first appearance in the Dunkard flora in the middle of the Washington Formation and continue into the Greene Formation, but in different beds from those containing wetland floral elements. Publication of these plants in the "Permian Flora" of Fontaine and White (1880) created an immediate controversy about the age of the unit because Callipteris conferta (now Autunia conferta) was, at the time, considered to be an index fossil for the base of the Permian. Subsequent collecting has revealed these callipterds to comprise four species: Autunia conferta, Autunia naumannii, Lodevia oxydata and Rhachiphyllum schenkii. Callipterids – and the conifers with which they are sometimes associated – are typically found in seasonally dry equatorial environments and most likely constitute an environmentally controlled biofacies. This biofacies is not well known, resulting in limited biostratigraphic utility.

Juvet Time Globe

National Museum of American History
In 1880 Scientific American, enthusiastically recommended Louis P. Juvet's time globe to its readers. It was, the magazine found, "a fit ornament for any library, a valuable adjunct in every business office, and a necessity in every institution of learning." The clockwork-driven globe was undeniably useful for studying geography, determining world time, and illustrating the rotation of the earth. The basis of its appeal, however, was even broader. Prominently displayed in the parlors and drawing rooms of Gilded Age America, the elegant time globe clearly demonstrated the wealth and culture of its owner. Available in a range of sizes and versions simple and ornate, the time globe consisted of three basic elements: a globe, a mechanism for rotating it, and a base. The globe most often featured a terrestrial map, but celestial globes were also offered. An equatorial ring indicated worldwide time and zones of daylight and darkness. A meridian ring supported a clock dial over the north pole. Concealed within the globe was a four-day, spring-driven brass movement that drove the clock dial and rotated the globe once every twenty-four hours. Manufactured for Juvet by Rood and Horton of Bristol, Connecticut, the movements featured a lever escapement and a balance wheel. Turning the feather end of the arrow-shaped axis wound the movement. Precisely when production of the globes began is uncertain. Juvet, a Swiss immigrant and a resident of Glens Falls, New York, first patented a mechanical globe in January 1867, and exhibited one at the Philadelphia Centennial Exposition of 1876. Probably sometime in 1879, Juvet formed a partnership with James Arkell. By the early 1880s, Juvet and Company of Canajoharie, New York, was making more than sixty varieties of globes. In October 1886, fire consumed the factory where the globes were assembled, ending their manufacture there forever. Pictured on the right. Overall measurements are 51 x 17 x 15 in..

Discriminatory power of different arthropod data sets for the biological monitoring of anthropogenic disturbance in tropical forests

Smithsonian Libraries
Arthropods were monitored by local parataxonomists at 12 sites of increasing anthropogenic disturbance (old and young secondary forests, savanna and cultivated gardens) at Gamba, Gabon. We report on the discriminatory power of different data sets with regard to the classification of sites along the disturbance gradient, using preliminary data accounting for 13 surveys and 142 425 arthropods collected by Malaise, pitfall and yellow-pan traps. We compared the performance of different data sets. These were based upon ordinal, familial and guild composition, or upon 22 target taxa sorted to morphospecies and either considered in toto or grouped within different functional guilds. Finally we evaluated `predictor sets' made up of a few families or other target taxa, selected on the basis of their indicator value index. Although the discriminatory power of data sets based on ordinal categories and guilds was low, that of target taxa belonging to chewers, parasitoids and predators was much higher. The data sets that best discriminated among sites of differing degrees of disturbance were the restricted sets of indicator families and target taxa. This validates the concept of predictor sets for species-rich tropical systems. Including or excluding rare taxa in the analyses did not alter these conclusions. We conclude that calibration studies similar to ours are needed elsewhere in the tropics and that this strategy will allow to devise a representative and efficient biotic index for the biological monitoring of terrestrial arthropod assemblages in the tropics.

Speciation Genes in Free-Spawning Marine Invertebrates

Smithsonian Libraries
Research on speciation of marine organisms has lagged behind that of terrestrial ones, but the study of the evolution of molecules involved in the adhesion of gametes in free-spawning invertebrates is an exception. Here I review the function, species-specificity, and molecular variation of loci coding for bindin in sea urchins, lysin in abalone and their egg receptors, in an effort to assess the degree to which they contribute to the emergence of reproductive isolation during the speciation process. Bindin is a protein that mediates binding of the sperm to the vitelline envelope (VE) of the egg and the fusion of the gametes' membranes, whereas lysin is a protein involved only in binding to the VE. Both of these molecules are important in species recognition by the gametes, but they rarely constitute absolute blocks to interspecific hybridization. Intraspecific polymorphism is high in bindin, but low in lysin. Polymorphism in bindin is maintained by frequency-dependent selection due to sexual conflict arising from the danger of polyspermy under high densities of sperm. Monomorphism in lysin is the result of purifying selection arising from the need for species recognition. Interspecific divergence in lysin is due to strong positive selection, and the same is true for bindin of four out of seven genera of sea urchins studied to date. The differences between the sea urchin genera in the strength of selection can only partially be explained by the hypothesis of reinforcement. The egg receptor for lysin (VERL) is a glycoprotein with 22 repeats, 20 of which have evolved neutrally and homogenized by concerted evolution, whereas the first two repeats are under positive selection. Selection on lysin has been generated by the need to track changes in VERL, permitted by the redundant structure of this molecule. Both lysin and bindin are important in reproductive isolation, probably had a role in speciation, but it is hard to determine whether they meet the strictest criteria of "speciation loci," defined as genes whose differentiation has caused speciation.

Spectrograph, DTM Image Tube

National Air and Space Museum
Original Image Tube Spectrograph built in the early 1960s by W. Kent Ford, Jr., which he then used in collaboration with Vera Rubin to explore an observational problem she had developed: to determine the detailed rotational properties of galaxies. The cascaded image tube developed by Ford at the Carnegie and then manufactered by RCA improved quantum efficiency of photographic detectors by over a factor of ten and made it feasible to perform difficult observational programs like this. Analysis of observational data from this instrument led Rubin to the conclusion that there was a huge amount of unseen mass distributed throughout the visible matter in galaxies causing them to rotate like rigid bodies. This observation yielded evidence for the existence of dark matter that stimulated general acknowledgement that it forms a majority of the mass in the Universe. For her revolutionary work, Vera Rubin was the second woman in history to be awarded the Gold Medal of England's Royal Astronomical Society. The spectrograph was originally on loan to NASM from the Carnegie Institution of Washington and has now been accessioned into the collection as it represents the successful application of electronic amplification technology that led to a profound change in our understanding of the nature of the Universe.

Mars orbital synthetic aperture radar: Obtaining geologic information from radar polarimetry

Smithsonian Libraries
Radar penetration of mantling layers, and scattering from buried objects or interfaces, is a topic of current interest in both terrestrial and planetary remote sensing. We examine the behavior of surface and subsurface scattering interfaces and the types of information that may be obtained from observations in different polarizations and wavelengths. These results are applied to the design of a future Mars orbital synthetic aperture radar (SAR), for which we draw the following conclusions. (1) Mapping of buried geologic features is best accomplished using VV polarization, at an optimal wavelength determined by the competing effects of antenna gain, attenuation in the dust, and the reduction in effective surface roughness with wavelength. P band frequencies (?1 GHz or less) offer the best opportunity for detection of moderately rough, buried features. (2) The relative roles of surface and subsurface scattering may be determined using measurements in HH and VV polarization, with a channel gain calibration better than 0.5 dB. (3) The thickness of a mantling layer (or ice mass) cannot be directly inferred from multiwavelength observations. Layer thickness may be inferred from the interferometric correlation of backscatter measurements collected on suitably spaced orbital passes, though the required phase measurement accuracy is challenging. While additional information may be gained by collecting scattering data in more polarizations or wavelengths, we suggest that the primary science goals of a Mars-orbiting radar could be accomplished by a single-wavelength system capable of collecting VV and HH polarizations with the calibration and orbit control needed to permit interferometric analysis.

Juvet Time Globe

National Museum of American History
In 1880, Scientific American enthusiastically recommended Louis P. Juvet's time globe to its readers. It was, the magazine found, "a fit ornament for any library, a valuable adjunct in every business office, and a necessity in every institution of learning." The clockwork-driven globe was undeniably useful for studying geography, determining world time, and illustrating the rotation of the earth. The basis of its appeal, however, was even broader. Prominently displayed in the parlors and drawing rooms of Gilded Age America, the elegant time globe clearly demonstrated the wealth and culture of its owner. Available in a range of sizes and versions simple and ornate, the time globe consisted of three basic elements: a globe, a mechanism for rotating it, and a base. The globe most often featured a terrestrial map, but celestial globes were also offered. An equatorial ring indicated worldwide time and zones of daylight and darkness. A meridian ring supported a clock dial over the north pole. Concealed within the globe was a four-day, spring-driven brass movement that drove the clock dial and rotated the globe once every twenty-four hours. Manufactured for Juvet by Rood and Horton of Bristol, Connecticut, the movements featured a lever escapement and a balance wheel. Turning the feather end of the arrow-shaped axis wound the movement. Precisely when production of the globes began is uncertain. Juvet, a Swiss immigrant and a resident of Glens Falls, New York, first patented a mechanical globe in January 1867, and exhibited one at the Philadelphia Centennial Exposition of 1876. Probably sometime in 1879, Juvet formed a partnership with James Arkell. By the early 1880s, Juvet and Company of Canajoharie, New York, was making more than sixty varieties of globes. In October 1886, fire consumed the factory where the globes were assembled, ending their manufacture there forever. Pictured on the left. Overall measurements are 55 1/2 x 17 x 17 inches.

Dip Circle

National Museum of American History
The Department of Terrestrial Magnetism of the Carnegie Institution of Washington bought this Kew pattern dip circle in 1919. The inscription reads "Dover, Charlton Kent, Circle 240." With four needles, tripod, case, Kew certificate of examination, and importation charges, it cost $184.70. The vertical circle is silvered, graduated to 30 minutes, and read by opposite verniers to single minutes. The horizontal circle is silvered, graduated to 30 minutes, and read by vernier to single minutes.
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