VOL. LXXXIV.] 



PHILOSOPHICAL TKANSACTIONS. 



389 



cally die isochronal property of spiral springs, though this property must be al- 

 lowed to exist in theory, whenever the forces of elasticity at the several angular 

 distances from the quiescent position are in the precise ratio of those distances. 



The vibration of a balance impelled by a single spiral spring only, has been 

 the subject of the preceding investigations ; but cases occur in which 2 or more 

 springs are employed in giving vibratory motion to the balances of watches. Not 

 to mention preceding instances, Mr. Mudge, an eminent watch-maker of the 

 present times, has invented a method of combining the action of spiral springs, 

 to impel the balance in each semi-arc of vibration, on a principle not more remark- 

 able for the novelty than it is for the ingenuity of the contrivance. The con- 

 sideration of this additional case will therefore not be thought foreign to the pre- 

 sent subject, especially as it may contribute to elucidate some circumstances 

 respecting the effect of springs on the vibrations of balances, which at the first 

 view are not at all obvious. Accordingly Mr. Atwood subjoins the application of 

 the foregoing investigations to this latter case. But the preceding determinations 

 may suffice for all useful purposes. 



XL Meteorological Journal, for the Year 1793, kept at the apartments of the 

 R. S., by order of the President and Council, p. \Qq. 



1793. 



January . . . . 

 February . . 



March 



April 



May 



June 



July 



August . . . . 

 September , . 

 October . . . . 

 November . . 

 December . . 



Whole year. 



Thermometer 

 without. 



o . - 



48 



52 



52 



6'o 



69 



72 



S9 



80 



66-.5 



6.5 



56 



53 





28 



30 



3 3 



33 



-14 



47 



54 



52 



4,' 



35.. 



31 



30 



ffi .bO 



37.6 



42 



41. j 



-15.5 



54.4 



59.1 



68 



63.7 



55.4 



54.3 



45.5 



42.9 



50.8 



Thermometer 

 within. 



ra be 



54 



57 



58 



59.5 



64 



6S 



76 



70.5 



66 



64 



6l 



60 



g.SP 



45 



49.5 



49.5 



50 



56 



57 



62 



63.5 



56 



56 



53 



50 



49.6 



52.5 



54 



55 



59-2 



60.6 



69 



66.3 



61.2 



60.6 



56.4 



55.1 



58.3 



Barometer. 



«2 ._j 



C3 bO 



as 



Inches. 



30.52 



30.22 



30.21 



30.27 



30.29 



30.20 



30 30 



30.28 



30.45 



30.48 



30.36 



30.38 



J2 

 bO 





Inches. 

 2898 

 29.29 

 29.07 

 29.22 

 29.24 

 29.68 

 29-74 



29.34 

 29.41 



29.22 



29.05 



28.72 



?; bp 



Inches. 

 30.16 

 29.8O 

 29.84 

 29.89 

 30.04 

 29-96 

 30.03 

 29.95 

 29.98 

 29.98 

 29.80 

 29.74 



29.93 



Hygrometer. 



O-a 



oj _bt 



■Si 



83 

 85 

 70 



72 

 74 

 73 

 t^2 

 84 

 83 



51 

 46 

 43 

 46 

 43 

 47 

 50 

 57 

 64 



OJ bo 



Rain. 



Inches. 



1.565 

 1.581 

 1.162 

 1.095 

 0.865 

 0.427 

 1.616 

 1.315 

 2.452 

 1.137 

 2.104 

 I.S09 



17.12s 



JCIL On the Conversion of Animal Muscle into a Substance much Resembling 

 spermaceti. By George Smith Gibbes, B.A., of Magdalen College, Oxford. 

 p. 169. 



It is a matter of great curiosity to observe; after any fact has been well ascer- 



