Januaey 31, 1896.] 



SCmNGE. 



175 



is the great eifect that the change of tempera- 

 ture has upon its elasticity. If a bar of alum- 

 inum and a bar of cast steel be tuned at a certain 

 temperature to exact unison, a change from 

 that temperature will affect the frequency of 

 vibration of the aluminum bar 2 J times as much 

 as the same change of temperature will affect 

 the bar of cast steel. 



A second physical article by Carl Barus gives 

 the results of experiments carried on, with the 

 aid of a fund from the Smithsonian Institution, 

 on the curl aneroid. The special object of the 

 investigation was to find what degree of con- 

 stancy and precision could be obtained from a 

 suitably modified Bourdon tube, or flattened 

 tube coiled in the form of a helix. A similar 

 tube had been used before successfully for high 

 pressures with, however, certain limitations 

 which do not exist in the case of low pressures, 

 for wliich it is now designed, e. g., when ex- 

 hausted for, use as an aneroid in registering 

 small changes of atmospheric pressure. Exper- 

 iments with simple curls are detailed, made 

 very thin by dissolving away the walls in acid. 

 Also other experiments with a counter-twisted 

 system ; that is, one supplied with a coiled 

 spring placed above and opposed to the flat- 

 tened and exhausted curl. The results of the 

 experiments with this form show that by it the 

 hurtful effects of viscosity and changes of tem- 

 perature can be reduced to a minimum, while 

 the sensitiveness of the instrument is increased 

 to a remarkable degree. G. W. Littlehales dis- 

 cusses from a mathematical standpoint the 

 problem of finding an isolated shoal in the open 

 sea which had been located by previous obser- 

 vation. He concludes that, under certain con- 

 ditions named, there would be one chance in 

 6,173 of finding it. This explains why navi- 

 gators often fail to find shoals shown on their 

 charts. H. B. Kiimmel gives a note on the 

 glaciation of Pocono Knob (Monroe county) and 

 Mounts Ararat and Sugar Loaf ("Wayne county), 

 in Pennsylvania, which have hitherto been re- 

 garded as having risen above the ice during 

 glacial times. The author's observations, how- 

 ever, lead him to conclude that the ice probably 

 covered the highest points of all these summits. 

 T. L. Walker gives the result of a study of 

 crystals of the platinum arsenide, sperrylite. 



from Algoma, Ontario. He also adds some notes 

 as to its occurrence, and notes the presence of 

 iridium and osmium in the matte from the 

 Murray mines, leading to the conclusion that 

 these metals are sometimes constituents of the 

 sperrylite. S. L. Penfield and E. H. Forbes de- 

 scribe the results of an investigation of the op- 

 tical properties of the members of the chrysolite 

 group of minerals as connected with their chem- 

 ical composition. It is shown that the mean 

 index of refraction, and also the strength of the 

 double refraction, diminish with decrease in 

 percentage of iron protoxide, FeO ; on the other 

 hand, the value of the optic axial angle (2V) in- 

 creases. With the FeO about 12 per cent. , 2V for 

 yellow equals nearly 90°. Chrysolites containing 

 less than 12 per cent. FeO have the crystallo- 

 graphic axis a for the acute bisectrix and are 

 optically positive with dispersion p < v, and 

 those richer in iron are optically negative with 

 dispersion p > z>. 



The concluding twenty-five pages of the 

 number are occupied with abstracts of papers 

 in other journals, notices of books, scientific 

 news, etc. 



ASTEOPHYSICAL JOURNAL, JANUABY. 

 Action of the Editorial Board of the Astrophysical 



Journal with Regard to Standards in Astro- 

 physics and Spectroscopy. 



The board of editors, who have had the ques- 

 tion under consideration for the past year, have 

 adopted for the magazine the following stand- 

 ards: 



The Roivland scale of wave-lengths, the unit of 

 wave-length to be Angstrom's, the ten millionth 

 of a millimeter, known also as the ' tenth- 

 meter. ' 



The kilometer as the unit of measurements of 

 motion in the line of sight. 



The hydrogen lines to be designated Ha, H/i(, 

 etc., beginning at the red end and continuing 

 through the entire series. Maps of spectra will 

 be printed with the red end on the right, and 

 tables of wave-lengths with the shorter wave- 

 lengths at the top. 



The hope is expressed that the action of the 

 editors will be concurred in by other astrono- 

 mers and physicists, and adopted in their publi- 

 cations. 



