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XV. Copy of Q. Letter to the Rev. Samuel ^'INCE, PbtmifTH 

 Professor of Astronomy, c^c. &'c., Camhridge, from 

 John Southern, Engineer , dated Birmingham, Janu- 

 ary 19, 1801.* 



Sir, 



Laving read with much pleasure your paper on Friction, 

 pubhbhed in the Philosophical Transactions, vol. Ixxv.f 

 I am mduced to trouble you with this letter, containing 

 an account of a few experiments made by me some years 

 since on the same subject, which were sugoested by your 

 elegant proposition, in terms equivalent to the following : 

 that if friction be an uniform iorce, a body falling by its 

 own weight, but resisted by friction, would nevertheless 

 be uniformly accelerated. If you think the account is 

 worthy the attention of the Roval Society, you will, per- 

 haps, do me the favour of presenting it to that learned 

 bodyt. _^:«._- 



ACCOUNT OF SOME EXPEIIIMENTS ON FraCTlON. 



In the neighbourhood of this place there are many mills 

 used for turning griiKJstoncs which have a very great velo-. 

 city, and which, from the facility of being detached in that 

 state from the mill, are peculiarly adapted to ascertain, or 

 rather to corroborate, your proposition, and also to deter-. 

 mine in such cases the real quantum of friction ; and I 

 therefore availed myself of the liberty, whicia I readily ac- 

 quired, to make experiments at one of them. Before I give 

 an account of these, it will be useful to give a description of 

 the apparatus employed in making them. (See Plate II.) § 



A, (Fig. 6.) the grindstone o^i inches diameter_, and 2Q^ 

 inches thick. 



B, its spindle (of iron). 



CC, the pivots or cylindric parts of the spindle, upoil 

 which it and the stone turned, exactly 3?, niches dia- 

 meter. 

 D, the pulley (of wood) upon the edge of which a lear 

 ther strap went round, or rather half round, by which 

 the stone was put in motion and continued so during 

 pleasure, and by slipping off which the stone was de- 

 tached iTom the miil, and suffered to turn freely till 

 the resistance of friction on the pivots of the spindl* 

 and of the air stopped it. 



• Communicated hy the Author. 



•f- See the picceding article, continued from our last number. 

 + Mr. \ incc, approving ir, did present it to tlie Royal Society. 

 § Inserted in our last Murnber. 



E, a 



