404 PHILOSOPHICAL TRANSACTIONS. [aNNO 1788. 



multiplied into a fraction whose numerator is difference between the density of 

 the body (d) and fluid (x') at that distance and denominator d, that is, as 





Many cases might have been given, in which the fluxional equations could 

 have been resolved ; but in general their fluents can only be found by means of 

 converging serieses. 



F7//. Experiments on Local Heat. By James Six, Esq., of Canterbury. 



p. 103. 



The following experiments are a continuation of those Mr. S. communicated 

 some time before, relating to the diversity of local heat in the atmosphere ; and 

 confirm, in a more particular manner, his former observations respecting a re- 

 markable refrigeration, which, in clear weather, takes place near the earth ; for 

 though its surface in the day-time is then most liable to be heated by the sun, 

 yet after that is set, and during the night, the air is always found coldest near 

 the ground, particularly in valleys. The experiments in the former paper were 

 made partly in autumn, and partly in winter ; and, the local variations differing 

 in some measure with the seasons, he was desirous of continuing a series of ex- 

 periments throughout one entire year. To this end therefore he suspended pro- 

 per thermometers in a shady northern aspect, in the open air, at different heights; 

 one in the garden at 9 feet, and another in the Cathedral Tower 220 feet from 

 the ground ; continuing his journal, with the omission of a few days only, from 

 July 1784 till July 1785. The result entirely corresponded with what was before 

 observed respecting the nocturnal diminution of heat, and the particular state of 

 the atmosphere requisite to produce it. From the 25th to the 28th of October, 

 the heat below in the night exceeded, in a small degree, the heat above, at which 

 time there was frequent rain, sometimes mingled with hail. From the 1 1 th to 

 the 14th, and also on the 31st, there was no variation at all ; during which time 

 likewise the weather was rainy ; all the rest of the month proving clear, the air 

 was found colder below than it was above, sometimes 9 or 10 degrees. On cloudy 

 nights, in June, the lowest thermometer sometimes showed the heat to be a de- 

 gree or 2 warmer than the upper one ; but in the day time the heat below con- 

 stantly exceeded the heat above more than in the month of October. 



Being desirous of knowing whether the nocturnal refrigeration increased on a 

 near^ approach to the surface of the earth, Mr. S. placed, in the midst of an 

 open meadow, on the bank of the river, 2 thermometers ; one on the ground, 

 and the other 6 feet above it ; with these, and the 2 others before mentioned, 

 one on the tower, and the other in the garden, he made observations from the 

 JOth to the 23d of October, 1786. Here he found, as before, the nocturnal 



