424 Intelligence and Miscellaneous Articles. 



renewing the im])ulse, the average rate of deviation per hour was 

 12°-8. Having been permitted through the kindness of J. D. Milne 

 Esq, and the Rev. J. Longmuir to attach the same bob to a vi^ire 

 of 30 feet in the Mechanics' Institution here, with the same extent 

 of arc I found the hourly rate on a motion continued for seven hours 

 to be 12°'6, which is exactly the rate computed from the sine of the 

 latitude 57° 9'. A nearer coincidence of experiment with theory 

 cannot in any case be expected. 



From the above-mentioned and other experiments similarly con- 

 ducted, it appears that the deviation is the same in every point of the 

 compass. 



By giving this paper a place in your journal you will honour 

 Your most obedient humble Servant, 



Alexander Gerard. 



Oct. 25. — To the above I would now add, that with the small arc 

 the condition of the body approaches nearer to that referred to in 

 Newton's Principia, Prop. 47, Book I. ; and that the apparent acce- 

 leration produced by the resistance of the air may account for the 

 discrepancy between the observed phsenomena and some of the for- 

 mulae given in your Number for August or September. — A. G. 



BRISTOL. BY THOMAS G. BUNT. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



A short time before I had concluded my pendulum experiments 

 in St. Nicholas Spire, I was requested by the Curator of the 

 Bristol Philosophical Institution to try what results I might be able 

 to obtain from a pendulum which had been erected there. The 

 suspending apparatus of this pendulum is precisely the same as 

 that which I last employed at St. Nicholas, and described in your 

 Number for July. The ball is an accurately turned sphere of lead, 

 weighing 35lbs ; the suspending wire is of bright iron ; and the length 

 of the pendulum, carefully computed from the number of its oscilla- 

 tions in a given time, is 22-73 feet. A pointed wire projects from 

 the bottom of the ball, and reaches to within about |th of an inch 

 of the azimuth circle, which is of 12 inches diameter, beautifully 

 engraved and printed on a card. Across the circle, fastened down 

 by a pin through its centre, is a moveable index of card, 1 inch wide, 

 divided lengthwise into inches, and laterally by parallel lines, yVth 

 of an inch asunder. By watching the motions of the wire over these 

 divisions the semi-axes major and minor (a and b) may be read off, 

 the former to tenths, and the latter to hundredths, of an inch. 



The Curator informed me, that the earlier trials of this pendulum 

 were very unsatisfactory. At that time it was suspended from the 

 floor of the room over the theatre, so as to be liable to disturbance 

 by persons walking upon it ; but on removing the suspending screw 

 from the floor, and attaching it to a strong bracket projecting from 



