May 19, 1887] 



NATURE 



61 



The eclipse being visible in Europe and from places so 

 readily accessible from England, no Government Expe- 

 dition will be sent out to observe it. It is not probable, 

 therefore, that any English astronomers will go so far east 

 as Siberia. It may be hoped that Russian astronomers will 

 make good this defect, especially as four of the principal 

 towns of Siberia lie on the shadow-track — Tobolsk, Tomsk, 

 Krasnoiarsk, and Irkutsk ; the first and third being close 

 to the central line, and the sun being eclipsed when nearly 

 on the meridian at Irkutsk. A series of Siberian sta- 

 tions is the more to be desired, since, as Prof. D. P. Todd 

 has pointed out in the American Journal for March, this 

 eclipse offers an exceptionally favourable opportunity for 

 a concerted scheme of observation. The path of totality 

 coincides in a most remarkable manner with the lines of 

 the Russian overland telegraph, so that it will be per- 

 fectly possible to select a series of stations in telegraphic 

 communication with each other, and extending over a 

 line of 100° of longitude, with an extreme difference in 

 the absolute time of totality of more than an hour and a 

 half. It appears. Prof. Todd learns from a letter from 

 Dr. S. von Glasenapp, that the Russian telegraph service 

 may be expected to give the use of its lines at the time 

 for astronomical purposes. It is certainly to be hoped 



that so unique an opportunity may not be lost ; for it 

 might well happen that some discovery, either in solar 

 research, or of a comet or intra-Mercurial planet, might 

 receive in this manner the most satisfactory confirmation 

 and development. 



The eclipse may also be well observed in Japan. On 

 the west coast, Niigata, one of the Treaty ports, lies well 

 within the shadow on the north, and Takata, a large 

 manufacturing town, on the south, the central line passing 

 through the large fishing-village of Idzumosaki, on the 

 high road between the two. The Island of Sado, opposite 

 to Niigata, which is free to foreigners, is wholly within 

 the shadow, the central line crossing Sawa Umi Bay. 

 The totality here lasts 198 seconds, with a sun 37° high. 

 On the east coast the important town of Mito lies almost 

 precisely on the central line. The duration here will be 

 192 seconds, and the sun 35° high. Japan, indeed, offers 

 advantages for observing stations superior to those ot 

 Perm, as the sun will be considerably higher, and the 

 duration 20 to 25 seconds longer. 



The following formulae, computed by Woolhouse's 

 method {Nautical Almanac, 1836), from the elements of 

 the eclipse given in the British Nautical Almanac, will 

 supply the means for the computation of the beginning 



30 Longed* Ea«t36orGr»en<>ich 'VO 



and ending of the total phase for any place not far from 

 Perm, lat. 58° 8' N., and long. 55" 12' E. :— 



Cos w = 52*926 - [i'8954o] sin / + [1*42842] cos / 



cos (Z - 68° 25'*i); 



/ = I7h. 40m. 13-05. :f [1*94168] sin w - [3*20536] sin / 



- [3"»503i] cos / cos (Z - 19° 47' -9). 



And for determination of the latitudes of the central line, 

 and of the north and south limits of totality in the longi- 

 tude of Perm : — 



I - [1*73180] for N. limit; 

 n cos (N + t) = < - [1*72367] for central eclipse ; 

 ( - [1 71538] for S. limit. 

 « cos N = [1*42842] cos (Z - 68° 25'*!) ; 

 n sin N — [1*89540]. 



As in similar formulae given in Nature for previous 

 eclipses / is the geocentric latitude, L the longitude from 

 Greenwich counted positive towards the east, and / results 

 in Greenwich mean solar time. Quantities within square 

 brackets are logarithms, not simple numbers. 



Similarly for places near Idzumosaki, lat. 37° 38' N., 

 and long. 138° 49' E., we have : — 



Cos w - + 53*9763 ~ [1*84932] sin/ 



+ [I '53239] cos / cos (Z - 24° 5i'*i) ; 

 / = I7h. 32m. 24*9s. q: [ I 99243] sin w - [3*45091] sin / 



- [3*85537] cos/ cos (Z + io°4'*7). 



And for central line and limits 



n cos (A'' + /) - 



- [1*74018] for N. limit ; 



- [1*73220] for central eclipse ; 



- [i 72408] for S. limit. 



THE STEERING OF H.M.S. "AJAX." 



WHEN H.M.S. AJax was first sent to sea, her steer- 

 ing qualities were found to be very defective, 

 especially at high speeds, the most objectionable and per- 

 plexing characteristic of her behaviour being a tendency 

 to require a large angle of helm to keep her on a straight 

 course. This helm tendency was sometimes on one side 

 and sometimes on the other, generally remaining the one 

 or the other for some time unchanged, but occasionally 

 changing sides without warning or apparent cause. On 

 such occasions, at full speed, the ship had been found to 

 fly off her course at a right angle before she could be 

 mastered by reversing the helm. 



In a lecture on this subject, lately delivered before the 

 Royal United Service Institution, Mr. R. E. Froude sum- 

 marised as follows the causes to which such behaviour might 

 be colourably attributed in ships of the type of the Ajax, 

 namely, flat-bottomed and full- ended, particularly in the 

 run: (i) want of "directive character" (as he phrases it) 



