378 Annual Report. 



which, from the authority thus communicated to them, the 

 Council think it advisable to correct. The first occurs in the 

 description of the Summer South-Easter at Cape Town, to 

 which there is ascribed a degree of regularity, as to its rise, 

 continuance, and character, which, though occurring occa- 

 sionally, is by no means constant. 



The second is, in stating the quantity of Wine introduced 

 into Cape Town for consumption and exportation, at ninety 

 thousand pipes, if this be not a misprint for 19 thousand, it is 

 excessively loeyond the truth. 



IV. General Physics, Hydrography, and Hydraulics. The 

 attention of the Institution was early in the last year directed 

 to the subject of deposits, in pipes and conduits conveying 

 water, and the President favored the Institution with a detail, 

 respecting observations made on that subject, at Grenoble, 

 in A.D. ISIO, offering results which bear great analogy to 

 those effects on the v/ater pipes in Cape Town, which have 

 excited so much attention. Specimens of incrustations 

 almost filling half the bore of the pipes, were exhibited by 

 Mr. Chisholm, the Superintendent of the Water Works, 

 who also stated his experience in respect to these deposits. 

 From his details he concluded : 



1. That in regard to the fountain water distributed over Cape 

 Town, it exerts no action, or only to a very small amount, in 

 those cases where the stream does not fill the pipe, so that a 

 considerable body of air travels with it. 



2. That in close or full pipes the quantity of action or 

 deposit, depends on the quantity of the water which traverses 

 the pipe, the obstructions accumulating most where the stream 

 runs quickest. 



It may be remarked in addition to these circumstances, that 

 the water leaves comparitively little sediment in the boilers of 

 the steam engines now at work here. 



The attention of the Members was at one Meeting directed 

 to the subject of artesian wells. It is well known, that by 

 boring through the strata of the earth, where the materials are 

 disposed horizontally, or slightly inclined to the horizon, water 

 has been found to spring above the surface. The softer and 

 looser beds, which are often inclosed between others that are 

 more compact, seeming in this case to serve the purpose of 

 reservoirs and conduits, to transmit the fluid from loftier regions. 



In this colony, the prevailing want of water may be supplied 

 by this means where similar circumstances occur ; but in 

 respect to the country in this neighbourhood, such instances 

 cannot be numerous. The leading formation being clay slate 

 highly inclined, on which there are raised, masses of very com- 

 pact quartz sandstone, forming caps or coverings, of which the 



