( 503 ) 



XXXIII. Description of a New Self-Registering Barometer. 

 By ROBERT BRYSON, F.R.S.E. 



(Read 2d January 1844.) 



ALTHOUGH many proposals have been made to obtain a series of hourly 

 meteorological observations by mechanical means, this desideratum has not, from 

 various causes, been completely attained. The chief obstacle to be overcome, in 

 such self-registering instruments, is the great amount of friction, which neces- 

 sarily vitiates all the results, more especially in delicate instruments, such as the 

 barometer and thermometer. 



Dr ROBERT HOOKE was the first to propose a self-registered series of meteor- 

 ological observations, by an instrument, which he quaintly called a Weather-wiser ; 

 but no further notice is taken of this contrivance than a short description in one 

 of his tracts, bearing the date 5th December 1678, which would lead us to believe 

 that the instrument was never used. The late ALEXANDER KEITH, Esq. of Ravel- 

 ston also proposed a similar contrivance, a description of which is contained in this 

 Society's Transactions, Vol. 4th. This contrivance, from the constant friction ex- 

 cited by the marker on the revolving paper, seems likewise to have been abandoned. 



The barometer now to be described does not seem liable to the objection of 

 the others. Fig. 1. exhibits a side-view of the barometer, with the clock-work 

 which moves the cylinder on which the observations are registered. A is the 

 fussee of a spring time-piece, placed between two brass frames, driving a pinion 

 B, which passes through the frame, and is pivoted into a small cock on the back- 

 plate, for the purpose of allowing the large horizontal bevel wheel C to pitch easily 

 into it. This wheel is, by the pinion B, made to revolve once during twenty-four 

 hours ; it carries twenty-four pins, placed at equal distances round its circum- 

 ference, and is fixed to the spindle L, which works in two puppets F and 0, the 

 upper extremity being shewn at R, after passing through the cylinder D. PP are 

 two milled nuts, which are used in adjusting the pitch of the wheel C into the 

 pinion B. 



D is a tin cylinder about 3 inches in diameter, having the hours marked 

 from 1 to 12 A. M. red, and from 1 to 12 p. M. black. This cylinder has a brass 

 tube soldered through its axis, which fits easily upon the upper part of the spindle 

 L. To enable us to put this cylinder always on at the proper point, a small pin 

 is fixed into the wheel, and may be seen in the figure near C. This pin fits 

 into a small aperture in the bottom of the cylinder, and prevents any lateral mo- 

 tion which would change the marking of the hours ; this steady pin prevents 



VOL. XV. PAET IV. 6 U 



