33(^ 



NA TURE 



[August i, 1907 



East India Company. He was among the foremost mathe- 

 maticians of his day, and had his life been prolonged he 

 would undoubtedly have risen to greater fame. 



No. 76 of the Publications of the Carnegie Institution 

 contains an account of a series of researches by Prof. 

 Theodore W. Richards, in conjunction with Messrs. W. N. 

 .Stull, F. W. Brink, and F. Bonnet, on rhe compressibility 

 of a large number of the elements. .\ very ingenious 

 apparatus was devised for making the measurements, and 

 the results obtained show that the compressibility of an 

 element is a periodic function of the atomic weight, and 

 probably associated with the same causes which determine 

 atomic volume and volatility. 



The July number of the Journal of Hygiene (vii., No. 3) 

 is devoted to reports on plague investigation in India. 

 Further experimental evidence is detailed of the trans- 

 ference of plague through the intermediary of the flea. 

 It is shown that close and continuous contact of plague- 

 infected animals with healthy animals, if fleas are ex- 

 cluded, does not give rise to an epizootic among the 

 latter, and that when fleas are present the epizootic, if it 

 docs start, varies in severity and rate of progress accord- 

 ing to the season of the year and the number of fleas 

 present. The season in which epizootics were readily 

 produced experimentally, and spread rapidly, corresponds 

 with that i.f the plague epidemic. 



A SECOND edition of vol. iii. of the " Descriptive and 

 Illustrated Catalogue of the Physiological Series of Com- 

 parative Anatomy contained in the Museum of the Royal 

 College of Surgeons of England " has been published. 

 The volume is sold by Messrs. Taylor and Francis. It 

 contains descriptions of the specimens in the section com- 

 prising the nerves of vertebrates not dealt with in vol. ii., 

 and also those in the section including the organs of special 

 sense. 



The eleventh edition, revised, of Mr. \V. T. Lynn's 

 " Celestial Motions " has just been published l_iy Messrs. 

 Samuel Bagster and Sons, Ltd. The price of this handy 

 little book of astronomy is 2s. net. 



An interesting article, by Mr. E. V. Heward, upon 

 the physical features of Mars, with particular reference 

 to the habilability of the planet, appears in the August 

 number of the I''orluii'hllv Kcvicw. 



D.-vniel's Comet (1907^). — Herr Kritzinger's ephcmeris 

 for comet 1907^ is extended lo August 19 in No. 4191 

 (P- 259, July 23) of the Astroiioinische .\achricliteti, and 

 a part of it is given below : — 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences in August: — 

 Aug. I. 4h. Venus and Jupiter in conjunction. Venus 

 0° 18' N. 

 ,, Daniel's comet very near Aldebaran. 

 2. I2h. 6m. Central transit of Saturn's Satellite Titan. 

 4. I2h. Vesia in conjunction with the Moon. Vesta 



0° 52' S. 

 „ I5h. 38m. to i6h. 20m. Occultation of x' Orionis 



(mag. 47). 

 ,, Juno very closely S. of <p Virginis (mag. 4'9). 



10. I4h. Mercury and Jupiter in conjunction. Mercury 



2° 6' S. 

 10-13. Epoch of August shooting stars, Radiant 

 45' + 57°. 



11. Uranus 1° S of 28 Sagittarii (mag. 5'6). 

 14. Daniel's comet near 7 Geminorum. 



17. i6h. 53m. to 2oh. 26m, Transit of Jupiter's Sat. 



III. (Ganymede). 

 iS. 9h. 51m. Central transit of Saturn's Satellite 



Titan. 

 20. I2h. 42m. Minimum of Algol ffl Persei). 

 23. 9h. 31m. Minimum of Algol (;8 Persei). 



NO. 1970, VOL. 76] 



Ephemcris 12/1. (M.T. Berlin). 



Aug. 



An observation made on July 19 gave corrections of 

 -I- 4s. and -fi'-g to the ephemeris, and on that date the 

 magnitude of the whole comet was recorded as 4-0. 



Apparent path of Daniel's Cornel (igo;*/). August 1-19, 1907. 



From the accompanying chart it will be seen that during 

 the period August 1-19 the comet's apparent path lies 

 between a Tauri and \ Geminorum, its declination varying 

 but Jjy a small amount. On the former date the comet 

 will rise about four hours, and on the latter about three 

 hours, before sunrise. 



The Heliomicrometer. — For the purpose of determining 

 the heliographic positions of flocculi on spectroheliograms, 

 quickly and accurately, Prof. Hale has devised an apparatus 

 which he calls the heliomicrometer, and of which he gives a 

 preliminary description in No. 5, vol. xxv., of the .Astro- 

 physical journal (p. 293, June). 



Briefly, it is a modification of an earlier instrument in 

 which the spectroheliograin was projected on to a bright 

 globe divided by meridians of latitude and longitude, the 

 positions of the flocculi being read off directly from the 

 globe. The angular diameter of the latter as seen from 

 the projecting lens was, essentially, equal to the angular 

 diameter of the sun as seen from the earth. 



In the present apparatus, images of the photograph and 

 the globe arc viewed with two similar telescopes, the two 

 images being brought into the same eye-piece. Immediately 

 in front of the plate to be measured cross-hairs are 

 mounted, and their intersection may be set on the par- 

 ticular flocculus to be measured by the observer operating 

 from the eye-piece ; during this process the bright image 

 of the globe is occulted. The image of the properly 

 adjusted globe is then admitted, and, by means of fine 

 motions — again operated from the eye-piece — the inter- 

 section of the central meridian and the equator is brought 

 into coincidence with the intersection of the cross-hairs. 

 The amount that the globe has been rotated in each 

 coordinate is then read off from circles fitted with 

 verniers, and thus the latitude and longitude of the 

 flocculus are obtained directly without any computation. 



In testing the heliomicrometer method against that of 



