14 



NAUURE 



\Nov. 7, 1878 



Prescott's book, Edison distinctly says : "I can lay no 

 claim to having discovered that conversation could be 

 carried on between one receiver and the other upon the 

 magneto-principle, causing the voice to vibrate the 

 diaphragm. . . . My first attempts at constructing an 

 articulating telephone were made with a Reis transmitter 

 and one of my resonant receivers. My experiments in 

 this direction, which continued until the production of 

 my present carbon telephone, cover many thousand pages 

 of manuscript." 



This last incidental remark, which there is no reason 

 to doubt, reveals the indefatigable character of the man. 

 The public see only the successful results, and many 

 doubtless imagine that these spring ready accomplished 

 from the fertile brain of Mr. Edison ; the truth is just the 

 reverse. It is a trite, but true observation, that success- 

 ful work in any direction, and notably in scientific 

 discovery, is the result of patient persistent toil. The 

 public look at the nugget, but not at the labour that has 

 won it. The fields of science are now so well trodden that 



Fig. 4. — Edison's pressure relay resembling one form of microphone. 



discoveries are not to be accidentally picked up, but only 

 reward those whose quest is most skilful and diligent. 



The extraordinary succession of valuable discoveries in 

 applied science which Mr. Edison has made can only be 

 the offspring of incessant work, profound technical know- 

 ledge, and that ready resource under difficulties which 

 characterises a mechanical genius. The conditions under 

 which such a man works are different from those of a 

 purely scientific investigator ; the latter publishes his 

 researches and thereby establishes his claim to the 

 priority of the work he has done ; the former can publish 

 nothing till the end he has in view is achiev^ed, and the 

 pecuniary benefit accruing from his labours secured by 

 legal processes. And because the reward sought in the 

 two cases is very different, the investigator must often 

 expect to see others reaping the benefit of applications 

 that may be made of his observations, and the inventor 

 ought not to grumble when he finds others claiming 

 credit for work he may previously have done, but for his 

 purpose found it necessary to keep, by him unpublished. 



W. F. Barrett 



OUR ASTRONOMICAL COLUMN 

 The late Solar Eclipse at Watson's Station. — 

 Prof. Watson made such excellent use of the brief period 

 of totality in the eclipse of July 29, that it will not be 

 without interest to record the circumstances under which 

 he observed. In a communication to M. Mouchez he 

 gives for his position at Separation, Wyoming Territory, 

 latitude 41° 45' 50", longitude 2h. im. 36s. west of Wash- 

 ington, corresponding to yh. 9m. 48 "is., west longitude 

 from Greenwich. Prof. Newcomb's corrections to Han- 

 sen's place of the moon at this time are — o"63s. in right 

 ascension, and + 3-3" in declination ; whence if we take 

 joh. 24m. Greenwich M.T. for a special calculation, we 

 have for the position of the moon, R.A. 8h. 38m. 11 -965., 

 deck + 19° 5' 59-3". Combining this with the sun's place 

 from Leverrier' s Tables and the Nautical Almanac semi- 

 diameters, there results 

 Be^nningof totaleclipse, July29...3h. 13m. 32-5 ) Mean times 



^-nd'ng 3^^- i6m. 24-0 fat Separation. 



Thus the duration of totality was 2m.5r5s. 



If for the Nautical Almanac values we substitute 



Leverrier' s serai-diameter for sun and deduce the semi- 

 diameter of the moon from her horizontal parallax with 

 Burckhardt's ratio, we find the times of beginning and 

 ending of totahty are respectively 3h. 13m. 32'os. and 

 3h. i6m. 24"5s., showing a duration of 2m. 52'5s. ; we 

 may therefore take 2m. 52s. for the interval which was 

 available to Prof. Watson in his search for intra-mer- 

 curial planets. The middle of totality occurred at 

 3h. 14s. 58"3s. M.T. at Separation, or at iih. 44m. 4i'9s. 

 sidereal time, when the sun's altitude was 44^°, and his 

 hour-angle 46^° W. 



Calculation of Excentric Anomalies. — The 

 number of bodies in the minor planet group is now 

 approaching two hundred, yet so far as their orbits have 

 been satisfactorily determined only two or three out of 

 this number have the angle of excentricity, as it is 

 termed, or sin - '<?, greater than 20'^, which corresponds 

 to (f = o"342. More than ten years since Mr. Godward, 

 of the Nautical Ahnanac Office, prepared some tables 

 for the direct computation of the excentric anomaly from 

 the mean to this limit of excentricity. His process is as 

 follows : — 



In orbits where the excentricity is not great, M, ti, 

 and V being the mean, excentric and true anomalies 

 respectively, and ^ the angle of excentricity — 

 tan \v = tan^ (45° + k<p) tan 3 M nearly. 

 Let M' be an angle such that 



tan ^v = tan (45° -A- i<p) tan 4 u 



= tan2 (45° + ^<p) tan [4 M + k{M' - M)\ 

 Then the Table contains \{M' — M) for any value of 

 up to 20°, the arguments being ^ M and \ 0. 



As an example of the use of this Table, suppose the 

 excentric anomaly of Juno is required for the time to 

 which the elements of the planet are reduced in the 

 Appendix to the Nautical Almanac for 1881. The mean 

 anomaly (= e - tt) = 168° 39' '43 and i0 = 7° 23''22, 

 then o , 



hM 84 1972 



\(M' — M) — 1 1 -42 from the Table. 



\M' 84 8-30 



t^n^M' 0-98858 



tan {45° + i <f)) 0-11325 



tan^M I-10183 : i.'j 



tan^z/ 1-21508 



lu 8°5 2864 



h'v 86 3074 



11 170 57-28 



V 173 i"48 



Here tan ^v\s obtained by adding together the two 

 previous lines, so that there is no subtraction in the 

 operation. 



Mr. Godward' s Table was printed by the Nautical 

 Ahnanac Office in 1866. It is applicable to all the 

 satellite-orbits showing excentricity, as Hyperion, where 

 (^ = 7°ii'. 



The Minor Planets. — From No. 100 of the Circular 

 zum Berliner astronomischen Jahrbuch it appears that 

 the small planet at first announced as No. 190 is proved 

 by Herr Leppig's calculation of its orbit to be identical 

 with No. 94 (Atirora) ; the succeeding discovery there- 

 fore takes its number, and for planets found since the 

 beginning of the summer, the numbers, names, and dates 

 will stand thus : — 



No. 



