393 
From another table of tests, I find that Smith's round wire 
rope, 1;^ inch in circumference, is equal in strength to a hempen 
rope three inches in circumference, both bearing a strain of 
2^ tons. A two-inch wire rope, and a six-inch hempen rope, 
bear an equal strain of 8 tons. A three-inch icire rope, and 
a nine-inch hempen one, bear an equal strain of 15J tons. 
And a 4 J inch wire rope is said to be equal to a 12 inch 
hempen one, both bearing a strain of 'do\ tons. 
In these several instances the size of the hempen rope is 
nearly three times greater than that of the wire rope ; and 
its weight per fathom is more than double, without any 
superiority in point of strength. 
I am sorry it is not in my power to furnish you with 
similar data, relative to Newall's wire ropes : for although I 
have received information from quarters where they are now 
on trial, (the substance of which will be given in the sequel,) 
yet I have never seen any authorized statement of the size, 
weight, strength, cost, and durability of Newall's wire ropes, 
as compared with the hempen ones.* I would therefore 
avoid even the appearance of unfairness towards the patentee, 
by declining to give currency to theoretical speculations con- 
cerning his invention, which have been indulged in by others, 
and shall confine myself to the mere narrative of practical 
trials. These, however, will be more appropriately noticed 
in a subsequent part of this paper ; and I proceed at present 
to describe Heimann's patent wire ropes, which are manufac- 
tured at Camberwell. 
Smith's ropes (as before stated) are made entirely of iron 
wire ; but Heimann's are composed partly of ivire and partly 
of hemp. 
A longitudinal heart or core of hemp is introduced, round 
which the iron wires are wound so as to produce greater 
compactness and evenness than can be attained in ropes made 
* See additional obgervations at the end of this paper. 
