650 
POPULAE SCIENCE EEVIEW. 
ciples^ and perfect as to its electrical conductivity and insula- 
tion_, it is required to lower the same through the sea to a 
maximum depth of two miles and a half^ so as not merely not 
to allow the insulating medium to be torn or stranded_, but so 
as not to bring its normal elasticity to play against the more 
tensile but perfectly inelastic material of the conductor. For 
if the core were lowered into very deep water_, hke that re- 
ferred to^ without further protection^ even supposing it to 
escape actual fracture by the adoption of extraordinary pre- 
caution_, and by the aid of fine weather_, it is evident that 
whenever_, as would be highly probable^ either in the act of 
paying out^ during the lifting, or manoeuvering of the ship, or 
even from the effects of its own weight, the gutta-percha 
sheath became extended to the limit of its elasticity, the 
copper in the centre would be stretched to a corresponding 
extent, and the tension being removed, the gutta-percha in 
returning to its original length would pull back the now elon- 
gated copper, which, thenceforward, would in every such case 
^ buckle up ^ and exert a constant lateral thrust against the 
gutta-percha; ending, probably, in its ultimate escape to 
the outside, and the consequent destruction of the core as an 
electrical agent. Moreover, in the event of an electrical 
fault being discovered in any submerged portion of the cable 
during the process of ^ paying out ^ in deep water, it is of 
paramount importance towards its recovery and repair that 
the engineer should have such an assurance in the quality and 
strength of his materials as will enable him confidently to 
exert a known force in hauling back the injured part, without 
apprehension of danger to the vital portion of the cable.^^ 
Such were the difiiculties which had to be provided for, and, 
in nearly every department, the utmost care was observable^ 
Men of the highest class were selected, and the Great Eastern 
started on her enterprise with every prospect of successfully ac- 
complishing the task of uniting Europe and America. The result 
is too familiar to all to require auy notice of it in this journah 
The Diary ’’ of Dr. E-ussell has made every one familiar with 
the progress of the experiment from the time the great ship 
commenced paying out the deep-sea cable, from the 23rd of July 
to the 2nd and 3rd of August, when we find, on the 2nd, at 
8 P.M., a record of — Signals from the ship unintelligible at 
noon. No communication with, or information received from, 
ship since. Cause unknown.^^ And again, on the 3rd, 11.30 
A.M. — No information received from the ship. Cause un- 
known. No communication with ship.^^ All was over. The 
electric nerve had ceased to throb. It lay dead, more than 1200 
miles in length, at the bottom of the Atlantic. Desiring to 
record the progress of Atlantic Telegraphy, descriptions have 
