314 Dr Pearson, On observations of the Transit [Jan. 20, 



of about seven miles. My observations vary between 18° 2V and 

 18° 31' North Lat. I have taken 18° 3' 20" as my basis of calcula- 

 tion, this being about the average given by the stars. Greater 

 accuracy is clearly of no importance. The Longitude is derived 

 from that of Rodney's statue in the town of Kingston, which was 

 determined by Lieut. Green, of the U. S. Coast Survey, two or 

 three years ago, by telegraphic signals made with extreme care, to 

 be 5 h. 7 m. 1071 s. W. of Greenwich. In my results I assume 

 that I was about If s. east of this, or in 5 h. 7 m. 9 s. E. Long, of 

 Greenwich : 5 h. 16 m. 30 s.* E. of Paris. 



My Local Time I have been able to determine with considerable 

 precision. From about Nov. 23rd to Dec. 2, and from Dec. 8 to 13, 

 I was continually taking morning and afternoon altitudes of the 

 Sun, as well as altitudes of the stars in the evening. From these 

 I inferred the best chronometer of the two which I had with me, 



rn. s. 



to be Nov. 25 a.m. 2 45^ slow on L. M. T. 



Dec. 1 „ 3 6 „ d.l.r. 3'4s. 



Dec. 13 „ 3 48^ „ „ 3-54s. 



Also, by the kindness of Dr Copeland and Capt. Mackinlay, from 

 the clocks of the Government Transit Expedition at Up Park 

 near Kingston, I obtained, Dec. 1st, Chronometer 3 m. 6 s. slow on 

 their local Time, their meridian being within half a second of my 

 own, and Dec. 13, 9 p.m. by Transits of <y 2 Ceti and a Arietis, their 

 clocks having been dismounted, 3 m. 49 s. which gives the chro- 

 nometer a losing rate of 3"44s. I have therefore assumed my 

 chronometer to have been 3 m. 24 s. slow on L. M. T. at the morning 

 contact ; and 3 m. 24^ s. in the afternoon ; which gives results 

 without fractions of seconds, which situated as I was it would be 

 needless to introduce. 



The actual times of contact I had intended to take from my 

 second chronometer, which has an extremely clear tick : un- 

 fortunately it stopped from the heat when it had been exposed 

 five or ten minutes to the rays of the Sun, and before the time of 

 the first contact; I was therefore compelled to use my watch 

 which I held in my hand, though I do not think that any error 



* Since my return I Lave found by the large Chart of Kingston Harbour, to be 

 seen in the University Library, that the Lighthouse which I mention is as nearly as 

 possible in 5 h. 7 m. 6 s. E. longitude reckoned by its vjosition as referred to Rodney's 

 Statue. But 7 m. xtanl^ gives •187m. or nearly Is. of time (a sea-mile = 4 s.) 

 as the difference between my own meridian and that of the Lighthouse. This 

 would imply that my own W. longitude was 5h. 7 m. 7 s. instead of 5h. 7 m. 9 s. 

 The position of the Government observatory at Up Park Camp appears from the 

 chart to be nearly on the same meridian as my own : and this agrees with the result 

 I obtained on the spot, by which I made the two agree within balf a second. The 

 L. M. T. therefore of my results must be increased in each case by two seconds. I 

 shall look with interest to see what longitude Dr Copeland gives in his published 

 observations. 



