PHILOSOPHICAL WRITINGS OF THE LATE DB. DALTON. 23 



the clock being duly regulated. It is well known that at the 

 summer solstice the clock is before the sun, and consequently 

 the equation of time is then to be added to the time per clock, 

 or mean time, to reduce it to apparent time. Hence the 

 equation of time being on the increase, the afternoons are 

 longer than the forenoons, and are increasing on that account. 

 And as the days decrease very slowly after the solstice, by 

 reason of the slow decrease of the declination, and the equa- 

 tion of time increasing fast, the length of the afternoons will 

 continue to increase after the solstice, till the decrease of the 

 lengths of the days balances the equation of time. Hence the 

 calculation will be easy to any one furnished with a nautical 

 ephemeris. For, as radius : tang. lat.=59° 56' :: tang. dec. : sin. 

 of ascensional difference. ♦ ♦ ♦ * From which it 

 appears that the afternoon of the 23rd of June will be the 

 longest of any in the year at that place." 



About this time still further honours awaited Mr. Dalton. 

 He had already established his reputation as a mathematician 

 and philosopher, and his efforts to obtain honourable distinc- 

 tion were now about to be crowned with success. In the 

 early part of 1793 he had the satisfaction of having had 

 awarded to him the " prize of six Diaries," for his solutions to 

 the questions proposed in the Gentleman* s Diary, Towards 

 its close he was honoured by being selected, on the recom- 

 mendation of Mr. Gough, as professor of mathematics in 

 Manchester New College ; and shortly after his removal to 

 Manchester, he himself added permanency to his character as 

 a natural philosopher by the publication of his still valuable 

 Essays on Meteorology, His contributions to the Gentle- 

 man* s Diary for this year are also tolerably extensive. They 

 embrace one query, one new mathematical question, and ten 

 solutions, including the prize, to those which had been pro- 

 posed in the previous Diary. The solutions to question 665, 

 and the prize, are inserted at length, the latter being honoured 

 with the first place; while his own question (No. 663) is ele- 



