292. Cloud Physics

Abstracts 279-299 33 279. Thermal Contact at Low Temperatures. United Kingdom. Mechanical heat switches are becoming of increasing importance in low-temperature calorimetry. A n apparatus has been made to study thermal contact for practical application to a heat switch and also to study the mechanism of heat transfer. The contact pressure is applied by a screw and measured by a strain gauge attached to a cantilever assembly. The thermal conductance of gold-gold, copper-copper, copperdiamond, and sapphire-sapphire contacts have been measured with this apparatus and are shown at various temperatures in the range up to 20 °K. G.S. Letter by R. Berman and C. F. Mate, Nature 182, No. 4650, 1662, 13 Dec. 1958. 33 280. Automatic Recording Vacuum Microbalanee. United States. A n automatic control and recording system for the null-type vacuum microbalance of Czanderna and Honig lanai. Chem. 29, 1206 (1957) ] has been assembled from commercial components. A variable permeance transducer is employed to detect beam movement and to control a force to restore the beam to the null position. This force is recorded in a selection of ranges extending from 0-20,000 t~g to 0-5 tzg with accuracies ranging from 0.1 per cent to 2 per cent of full scale. On the most sensitive settings the balance can detect weight changes as small as 0.01 t~g in loads up to 1 g. Stabilities of 0.1 /~g have been observed for periods of many hours on the most sensitive ranges. The balance is undamped, and no corrections are made to the restoring force if beam oscillation is centered about the null point. (Author) C. N. Cochran, Rev. Sci. Instrum. 29, 1135, Dec. 1958. 33 281. Electron-permeable Window for Cathode Ray Tubes. United States. J. Seehof, S. Smithberg and M. Armstrong, Rev. Sci. Instrum. 29, 776, Sept. 1958. 33 282. Low-tempe:,ture Optical Window Seal used at 80 °K. United States. Note by J. Willis, Rev. Sci. lnstrum. 29, 1053. Nov. 1958. 33 283. Vacuum Plant for Crystal Pulling. In order to satisfy the purity requirement in the production of semi conducting devices based on Ge or Si material apparatus was developed to grow single crystals of these materials in a high vacuum by a n u m b e r of different methods. H. Bumm, Vakuum-Technik8, 12-15, 1959. 33:46 284. Mica as Constructional Material for use in High Vacuum. The author discusses all technological questions related to this topic with the usual thoroughness covering : origin, composition, fabrication, physical and chemical properties, degassing, surface treatment, seals of mica with glass or metal, special applications. The production and properties of synthetic mica is also dealt v~ith. W. Espe, Vakuum-Technik 8, 15-19, 1959; 8, 29-38, 1959; 8, 67-76, 1959. 33 : 23 Transmission Specimen Holder for Electron Diffraction. Abstr. No. 207.

34.

H i g h A l t i t u d e and S p a c e T e c h n o l o g y

34 : 51 285. Stratospheric Fallout of Strontinm-89 and Barinm-140. Lois Fry and P. K. Kwroda, Science 129, 1742-1743, 26 June 1959.

247

34 : 58 286. Concentrations of Radioactive Materials in the Air during 1957. Luther B. Lockhart, Jr., Science, 128, 1139, 7 Nov. 1958. 34:51 287. Mass of the Moon from Satellite Observations. W. J. Gallagher, Science 128, 1207, 14 Nov. 1958. 34 288. Ground Rules for Space Research. J. T., Science 128, 1479, 12 Dec. 1958. 34 289. Radar Echoes from Venus. R. Price, P. E. Green, Jr., T. J. Goblick, Jr,, R. H. Kingston, L. G. Kraft, Jr., G. H. Pettengill, R. Silver, and W. B. Smith, Science 129, 751-753, 20 Mar. 1959. 34 290. Effect of Transverse Atmospheric Drag on Satellite Orbits. W. A. Wildhack, Science 128, 309-310, 8 Aug. 1958. 34 291. Optical Tracking of Artificial Earth Satellites. Fred L. Whipple, Science 128, 124-129, 18 July 1958. 34 292. Cloud Physics. Henry G. Houghton, Science 129, 307-313, 6 Feb. 1959. 34 293. Earth Oblateness in Terms of Satellite Orbital Periods. Leon Blitzer, Science 129, 329-330, 6 Feb. 1959. 34 294. Frontal Cloud System Pictures obtained by Rocket. Science 129, 198-200, 23 Jan. 1959. 34 295. " I G Y " Conference in Moscow. Homer E. Newell, Jr., and J. W. Townsend, Jr., Science 129, 79-84, 9 Jan. 1959. 34 296. International Geophysical Year. Hugh Odishaw, Science 128, 1599-1609, 26 Dec. 1958. 34 297. International Geophysical Year. Hugh Odishaw, Science 129, 14-25, 2 Jan. 1959. 34 298. Modifying Weather on a large Scale. H. Wexler, Science 128, 1059-1063, 31 Oct. 1958. 34 : 12 Density Determinations Based on the Explorer and Vanguard Satellites. Abstr. No. 137. 34:17 Atmospheres of other Planets. 35.

Abstr. No. 153.

I m p r e g n a t i o n and P o t t i n g

35 : 56 299. Vacuum Drying. Short account of the use of vapour booster pumps in plant intended for the drying and impregnation of electrical components. J.N. Engineer 206, 5361, 660, Oct. 1958.