Astronomy,

at a Mean between the greatestleast : All which Particulars constitute

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the Equator. But since R O = P H ru 15 Degr eeS t- j.Arch O R is less than OV, and so the Tropic ^will not touch the Circle M V at all; which sh eWS ^, 7 ifor some Time in the Middle of Summer there isj niNight : And this happens between May 23 andSee my Synopsis Scienti^e Coelestis, on aImperial Sheet, New-Stjle. .use

18. Moreover it is evident that C F =K G ? fMb'PL is parallel to Æ Qthe Time, however, of d e c sing C F and K G will not be the fame ; from ^it appears there is a certain Parallel in which th e s\light will be the least of-all, and another in which 1be a Maximum or greatest. The former is wh e 0 (Sun has 6? st South Declination, viz. in Libs?, fgst'Pisces X I7 P 30', which happens March 7,her 9, in the present Age : And ’tis plain thelight is greatest of all in the Parallel which touchPoint V, on May 23 and July 22 , as aforesaid. ^ isHow the Time of the least Duration ofinvestigated may be seen in the best manner in'P r 'gory’s Elements of Astronomy ; and I would have pyr,at here, but that it is very tedious, and in itself a

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ter of little Importance.

19. It is a Problem of much greater ConfA^ u ,and Curiosity, to determine the Ratio or Prop° rtl pjffieat which any Place receives from the Sun in a ^j eI £<bof the Year. Tn Order tn f-hic if must he CO#**

In Order to this it must be con ^ ^pthat the Quantity of Heat will be as the Time-, ifpose the Sun to have the same Altitude ; and as, f & iftf the Altitude , if the Time be the fame, ThcCT^ji)neither the Time nor Sine of the Altitude bethe Quantity of Heat will be as the Rectangle 0duct of both. y . i$

20. Therefore let a — Sine of the Latitude JE . ^ r,Co-sine (or Sine of Z N) = b ; the Sine of N ®and of its Complement (or Declination) S DfTSine of the Hour from Noon (or Angle Æl'P' M