174 Intelligence and Miscellanies. 
most correct and important.” It is not possible to do jus- 
tice to the statements of Mr. Walker without copying his let- 
ters entire. The most important results however are that 
cast iron pipes of any necessary diameter, even to two or 
three feet, may be employed—that their strength is suffi- 
cient to resist any desired pressure, when the thickness of 
their sides is very trifling, three quarters of an inch being 
sufficient for pipes of twenty inches diameter—three eights 
of an inch for ten inches, and three sixteenths for a five inch 
casting of one foot diameter and a half inch thick, is capa- 
ble of resisting: the tenacity of a square inch of the best 
cast iron, having been found by experiment to exceed twen~ 
thousand pounds’’*—that the joints of the pipes can be 
rendered impervious and secure—that the iron is very en- 
during—imparts no disagreeable taste to the water—is, when 
properly prepared, always to be depended on, and in the 
. — of years is more economical than any aaner sub- 
The joint used i in London, fo or connecting the pi — is the 
spigot and veveanda made tight in some cases, by lead cast 
around, a hers by a cement which is composed of two 
pounds ora ats Seeaaten with one hundred pounds of borings 
of iron, with the addition.of a little sulphur. These mate- 
rials are mixed with water which “ oxidizes the iron, and 
in a short time the mixture becomes extremely hard and 
quite impervious to water 
When lead is used it is ; contracted by cooling, and it is 
necessary to upset the joint with a hammer and chisel. 
The following extract of a letter to the Editor, dated, 
December 25, 1822, from Mr. Vaux, contains much valua~ 
ble information. 
“Our experience I consider to be decisive, especially in 
aut to the all important matter of the joints of the con- 
ults 
and cocks is made by the hydraulic pen 
dens sent out ps we Mr. alker to Philadelphia, aes proved by a press 
equal to a column of water of three hundred feet i in height, that is of the 
weight fi ares or ten atmospheres. 
