90 REPORT — 1844. 



shocks Lady Moncrieff felt in Perth (about twenty-two miles east of Comrie) ; 

 she was in church at the time, but it was not generally perceived by the con- 

 gregation. I learn that this shock was felt also at Callendar, about fifteen 

 miles south-west of Comrie. 



I am happy to tell you that I felt one of these earthquake shocks last night 

 at 8'" 50' P.M. I was in Lawers House at the time, which is (as you know) 

 about two miles east of Comrie. The noise was like that produced by the 

 rumbling of a cart over a pavement beneath the house ; it continued for about 

 four seconds ; it was loudest in the middle. Its progress was distinctly from 

 the westward, and at a great depth below the house. There was neither un- 

 dulation nor concussion. I could form no opinion, from the nature of the 

 noise, what was the agent which caused it. 



This morning I met a gentleman who was to the south of Comrie (about 

 two miles) when it occurred ; he perceived the course of the noise to be from 

 the north. At Ardvoirlich (about eight miles west of Comrie) the same noise 

 was perceived. 



The barometer was falling all yesterday afternoon, after having been for 

 some days remarkably high, and before seven o'clock this morning it had 

 fallen three-fourths of a tenth more. Yours very truly, 



To the Rev. Dr. Buckland. David Milne. 



Report of a Committee appointed at the Tenth Meeting of the Associa- 

 tion for Experiments on Steam-Engines. Members of the Com- 

 mittee -.—The Rev. Professor Moseley, M.A., F.R.S. ; Eaton 

 HoDGKiNSOXj Esq., F.K.S. ; J. S. Enys, Esq., F.G.S. ; Professor 

 Pole, F.G.S. f Reporter). 

 Your Committee, in reporting the progress of the experiments entrusted to 

 their care, have the pleasure of stating that they have succeeded in accom- 

 plishing the principal object which has engaged their attention during the 

 past year ; namely, to ascertain by actual experiment the velocity of the 

 piston of a single-acting Cornish pumping-engine, at all points of its stroke. 



Unfortunately, however, from delays and accidents, arising from causes in- 

 herent in the delicate nature of the operations required and the machine used, 

 there has not been yet time to obtain the data and work out the calculations 

 necessary for comparing the results of experiment with those of theory, and 

 by that means eliciting the useful information which it is hoped this com- 

 parison will offer to practical science. 



The velocity-measuring machine constructed by Breguet of Paris, under 

 the kindly proffered direction of M. Morin, was received a few months ago. 

 It is on the same principle as those with which the beautiful experiments of 

 M. Morin on friction were made, and which are described minutely in the 

 works of this writer (Nouvelles Experiences sur le Frottement, or Descrip- 

 tion des Appareils Chronoinetriques). These may be referred to for a full 

 and complete explanation of the construction and action of the machine, but 

 the principle of it may be briefly explained as follows. 



A circular disc, covered with card or paper, is made to revolve with a utii- 

 form motion by means of clockwork regulated by air-vanes. Plate XXV. 

 Upon this disc, a revolving pencil, whose motion is caused by and corresponds 

 with that of the body whose variable velocity is to be measured, describes a 

 curved line : and from this curve, which results from a combination of the 

 variable with the uniform motion, the velocity may be easily ascertained by 

 processes and formulae adapted to the purpose. 



This beautiful and ingenious contrivance, by which spaces described in . 



