108 THE WATER RAM. 



fixinc; of a ram, when I have spoken of the pipe for Gonductin^ 

 the water from the reservoir of compressed air to the place 

 required : for what I shall say of its thickness will be applica- 

 ble to that of the body of the ram, of whlcli I have promised to 

 speak, with this difference only, that the tunnel ought to be 

 nearly double the thickness of the ascending pipe, paying regard 

 likewise to the proportion required by the difference of 

 .diameter. 



To the head of the ram I add a piece of this tunnel, to which 

 the rest may be soldered. This serves as a guide for the dia- 

 meter, which ought to be the same, as well as for the thick' 

 ness, if the tunnel be made of the same material as the head 

 of the ram. 

 Pule for ra'cu- Should this not be the case, the following are the principles, 

 ifessofth- '*^ ' ^'^ which the thickness of the material employed should be 

 pipes. calculated. If wc know the thickness of a pipe of given sub- 



stance in a given experiment, and the height of tlie coluam of 

 water, the pressure of which it bore without bursting, \ve may 

 by this proportion the thickness of the pipe to be made to the 

 pressure it will have to sustain, and the diameter given it. 



For example, we know that a leaden pipe a twelfth of an 

 inch thick and an inch in diameter has supported a column of 

 water of 50 feet; and if we would know the thickness requir- 

 ed to support a column of 100 feet with the same diameter, 

 viG must multiply the preceding thickness by the ratio of 100 

 to 50, that is by 2. If wc would alter the diameter and not 

 the hcip;ht, wc must multiply the preceding thickness of the 

 ratio of the diameters ; so that if the diameter were increased 

 to 4 ifiches, the thickness roust bc-^^j- of an inch. If the pres- 

 sure and the diameter be both increased, the thickness must 

 be increased in the ratio of both. 



Nothing can be more simple than this calculation ; and to 

 avail ourselves of it we need only know the pressure thnt pipes 

 of different substances have sustniucd with a given uiatnctei". 

 This the following table will show : 



Table of tl e A pipe -J^ of an inch thick and an inch in diameter, feet. 



streri^fh ot of copper, supported a column of water of 400.' 



A pipe of the same dimensions of brass of a g,ood 



quality, cibout a fourth less, qr oOO. 



The 



