ON THE DETERMINATION OF TRANSATLANTIC Lu.VilTlbES. 401 



The difference of the Personal Equation in time determinations between Mr Dee.. 

 and Mr. Goodfellow has been computed from observations made by them at the I in- 

 bridge Observatory on three nights, viz. May 13, 17, and IS. On May I.;. alternate 

 tallies were taken by them, sometimes one and sometimes the other leading On 

 May 17 and 18, the first and last tallies were taken by one observer, and the three 

 middle tallies by the other. Twenty-six stars were observed on each of th night- 



The difference of the Personal Equation in time determination betwc Mr. (iood- 

 fellow and Mr. Austin was computed from observations made by the first method on 

 May 15, and by the second method on May 17 and 18. 



The following results were obtained : 



DEAN — GOODFELLOW. 



1870. May 13 — o!o6G ± .001 



" 17 —0.023 ± .<Mi8 



« 18 —0.009 ± .006 



Mean —0.033 ± .012 



Mr. Dean records a transit earlier than Mr. Goodfellow by .033 of a second. 



AUSTJN — GOODFELLOW. 



1870. May 15 +0.129 ± .011 



« 17 +0.163 ± .015 



k 18 + - 144 ± - 008 



Mean +0.145 ± .007 



Mr. Austin records a transit later than Mr. Goodfellow by .145 of a second. 

 These results were calculated by the formula 



(M 1 —M 2 ) + (F 1 -F 2 ) secS=±* 



in which M x represents the mean of the observed threads by the observ r who led, 

 and M 2 the mean of the observed threads by the observer who followed ; and /, sec 5 

 and F 2 sec 8 the corresponding reductions to the mean of all the threads On May 13 

 and 15,^ - F% was equal to _ 0°.093 ; and on May 17 and 1^/,-Jl was equal 

 to - 0'.060 ; Coast Survey Transit No. 5 being used on all the nights. 



2. If the electrical current sent through the main line were able to operate a re ay- 

 magnet, and through it to control the local circuit and battery It migh reco^ *elf 

 upon the chronogr°a P h at the place where it is received , as it *. at th p^e £ 



which it is sent. 



way in which they are recognized 

 vol. ix. 64 



and registered is described on page 44" 



The 

 A 



