14 Professou Rankine on the Stability 



Mr. Alex. Harvey exhibited and described Mr. Kennedy's Water 

 Meter. 



There was presented to the Society, in name of His Royal Highness 

 Prince Albert, a Copy of the Natural History of Deeside and Braemar, 

 by the late Dr. M'Gilvray, printed by command of Her Majesty. The 

 Librarian was instructed to acknowledge receipt of the work to the 

 Publishers, in terms of a request to that effect. It was agreed that 

 the work should not be allowed to be taken out of the Library. 



March 5, 1856. — The President in the Chair. 



Mr. Robert Blackie presented to the Library the Supplementary 

 Volume of the Imperial Dictionanj, for which the thanks of the Society 

 were voted to Messrs. Blackie, the Publishers. 



Dr. Anderson read a paper " On Bone Oil and its Products." 

 Professor Macquorn Rankine described some experiments on the 

 Pressure sustained by Structures of Brickwork, with reference to Fac- 

 tory Chimneys. 



On the Stability of Factory Chimneys. By W. J. Macquoen Rankine, 

 LL.D., r.R.SS. L. & E. 



Chimnets are exposed to the lateral pressure of the wind, which, 

 without sensible error in practice, may be assumed to be horizontal, 

 and of uniform intensity at all heights above the ground. 



The surface exposed to the pressure of the wind by such structures 

 is usually either flat, or cylindrical, or conical, and differing very little 

 from the cylindrical form. Octagonal chimneys, which are occasionally 

 erected, may be treated as sensibly circular in plan. The inclination 

 of the surface of a tower or chimney to the vertical is seldom sufficient 

 to be worth taking into account in determining the pressm-e of the 

 wind against it. 



The greatest intensity of the pressure of the wind against a flat 

 surface directly opposed to it, hitherto observed in Britain, has been 

 55 lbs. per square foot ; and this result (which is given on the authority 

 of Dr. Nichol) has been verified by the effects of certain violent storms 

 in destroying factory chimneys and other structures. 



In any other climate, before designing a structure intended to resist 

 the lateral pressure of wind, the greatest intensity of that pressure 

 should be ascertained either by direct experiment, or by observation of 

 the effects of the wind on previous structures. 



