ASTRONOMICAL PHENOMENA AND PROGRESS. 



49 



al sum of $200,000 to be paid in three annual 

 installments ; this sum he directs to be kept 

 invested as a permanent fund, the income of 

 which shall be applied from time to time to 

 the purchase of books and the maintenance of 

 the library, with liberty to expend not exceed- 

 ing $25,000 of the capital in the purchase of 

 books. 



ASTRONOMICAL PHENOMENA AND 

 PROGRESS. Solar Researches. In the Amer- 

 ican Journal of Science and Arts, for March, 

 1875, Prof. S. P. Langley, of the Alleghany Ob- 

 servatory, gives an interesting account of his 

 recent solar researches, with the conclusions 

 which he derives from the facts of observation. 

 His results are briefly stated as follows : 



1. The spot phenomena observed and described 

 seem inconsistent with the theory of a liquid or vis- 

 cous solar shell ; or at least such a stratum must, if 

 it exist, be at a considerable distance below the sur- 

 face of the photosphere. 



2. It seems difficult to reconcile the bright, sharp- 

 ly-defined inr/er penumbral edge, and the regu- 

 lar structure discerned in the umbra, with another 

 view, in which this umbra is a sort of stagnant pool, 

 formed by cold vapors, or clouds, which have set- 

 tled there after depressing the general surface by 

 their weight till the penumbral slope is determined. 



3. Finally, it seems to be little more than a sum*- 

 mary of the facts of observation to say that traces 

 of a vertical action are found throughout the spot, 

 and especially in the umbra. The theory which re- 

 gards cyclonic or vertical action as a prominent agent 

 in determining the forms we have studied, appears 

 then to be in closer accordance with observation than 

 the former 



The Sun's Diameter. The Astronomische 

 Naclirichten, No. 2,040, contains a discussion, 

 by Dr. Fugh, of the Greenwich solar observa- 

 tions from 1836 to 1870. The mean apparent 

 diameter derived from 6,827 measurements is 

 32' 2. "99 a value somewhat less than that 

 adopted in the American Ephemeris. 



The Late Transit of Venus. The discussion 

 of the observations of the transit of Venus in 

 1874 has not yet been completed. M. Puiseaux, 

 however, has given the result derived from the 

 observations at Peking, lat. 39 54' N., long. 

 7"' 46 m - E., and those at St. Paul, lat. 38 43' 

 S., long. 5*- 10 m> E. The four contacts were 

 observed at the former station, the two inter- 

 nal at the latter, and a large number of photo- 

 graphs were obtained at each. The parallax 

 derived from these observations is 8."879, cor- 

 responding to a mean distance of about 91,- 

 800,000 miles. 



The principal stations at which successful 

 observations were obtained are given below ; 

 together with a brief account of the work ac- 

 complished at each. The object of the photo- 

 graphs, it may be proper to remark, is to de- 

 termine the exact path in which the planet 

 crossed the sun's disk. The rate of Yenus's 

 motion being well known, the photographs of 

 the sun and planet, taken at accurately-record- 

 ed times during the transit, will enable as- 

 tronomers to determine, by microscopic meas- 

 urement, the precise distance between the 

 VOL. xv. 4 A 



centre of Venus and the centre of the sun on 

 each of the photographic plates. With a se- 

 ries of pictures from the different stations the 

 object sought may therefore be accurately de- 

 termined. 



In the following list of stations, those of 

 each hemisphere are arranged in the order of 

 distance from the equator : 



NOETHEEN HEMISPHEBE. 1. Honolulu. Lat. 

 21 18,' long. 10 h> 31 ra - W. English station. 

 Observers, Captain G. L. Tupman, Lieutenant 

 F. E. Ramsden, and Mr. Nichol. The first 

 two contacts were well observed, and the com- 

 plete disk of the planet was seen twelve min- 

 utes before the internal contact. The first 

 contact was observed l m - 43"-, and the second, 

 2 m- 55.7 8 ', later than the computed time as 

 given in the English Nautical Almanac. Dur- 

 ing the passage of the planet across the limb 

 of the sun 40 micrometer measures were taken 

 by Captain Tupman and Mr. Nichol. 



2. Near Thebes, Egypt. Lat. 25 43', long. 

 2 u. 10 m. E> English station. Observers, Cap- 

 tain W. de W. Abney and Colonel Campbell. 

 The last two contacts were well observed, and 

 50 photographs were secured. The observers 

 at the Russian station in the same vicinity were 

 also successful. 



3. Roorkee. Station of the British East India 

 Company. Observers, Colonel Tennant, Cap- 

 tain Campbell, and Captain Waterhouse. One 

 hundred and nine photographs were obtained. 



4. Suez. Lat. 29 58', long. 2 h - 10 m - E. Eng- 

 lish station. Chief observer, Mr. Hunter. The 

 last two contacts were successfully observed. 

 "For some time after contact, 1 ' Mr. Hunter 

 reports, "the edge of Venus was brilliantly 

 illuminated, that edge which had just left the 

 sun, so that for a little I thought the sun was 

 appearing behind it still, although the cusps 

 were then well marked. It was a clear, silvery 

 light, like the edge of a cloud." 



5. Cairo. Lat. 30 6', long. 2 h - 5 m - E. Eng- 

 lish station. Observers, Captain C. Orde 

 Browne and Mr. Newton. The last two con- 

 tacts were well seen. 



6. Ispahan. Lat. 32 40', long. 3 h - 27 m> E. 

 German station. Nineteen photographs were 

 obtained. 



7. Nagasaki. Lat. 32 45', long. 8 h - 39 m - E. 

 American and French station. The American 

 observers were : Prof. George Davidson, United 

 States Coast Survey, chief, with O. H. Tittman 

 and W. S. Edwards, assistants ; S. R. Seibert, 

 of the Treasury Department, Washington, chief 

 photographer, with Messrs. Williams and Lodge, 

 assistants. The second contact was well ob- 

 served ; the first and third were partly, and the 

 fourth wholly, obscured by clouds. A summa- 

 ry of results is thus given by Prof. Davidson : 



During the day there was no time after 10 A. M. 

 when the sun shone from a blue sky. The upper 

 stratum of clouds acted as a screen to the sun's heavy 

 rays, and the atmosphere was quite steady. Objects 

 at a distance were dark, but clearly defined. Of pho- 

 tographs, we got none near first contact, and only 

 began to receive them when the planet was half on. 



