. Electric railway gazette . WfMrefM cLccri Fig. I. The temperature and pressure of the atmos-phere did not produce any sensible change, buthe concluded that the dissipation was nearly pro-portional to the cube of the quantity of moisturein the air. In examining the dissipation which takes placealong imperfectly insulated substances, he foundthat a thread of gumlac was the most perfect ofall insulators, as it insulated ten times as well asa dry silk thread, and that a silk thread coveredwith fine sealing-wax insulated as powerfully asgumlac, when it had four times its length. Hefound that the
. Electric railway gazette . WfMrefM cLccri Fig. I. The temperature and pressure of the atmos-phere did not produce any sensible change, buthe concluded that the dissipation was nearly pro-portional to the cube of the quantity of moisturein the air. In examining the dissipation which takes placealong imperfectly insulated substances, he foundthat a thread of gumlac was the most perfect ofall insulators, as it insulated ten times as well asa dry silk thread, and that a silk thread coveredwith fine sealing-wax insulated as powerfully asgumlac, when it had four times its length. Hefound that the dissipation of electricity along in-sulators was chiefly owing to adhering moisture,but in some measure also to a slight conductingpower. History as far as the writer knows, is silent asto the first attempts at insulating wires commer-cially, for electrical purposes, but as these re-marks apply entirely to underground construc-tion, we will refer only to the earlier efforts in. Fig. 2. that line, accepting at once the conclusion thatVi wires had perforce been insulated. In 1829 Henry used insulated wire for experimentalw work. It was during the year 1832 that Prof. iVIorsefi first conceived the idea of underground trans-n mission of electricity, and among his earliest1 plans we have a suggestion of the conduits of to-J day, and as these drawings are of historical im-1 portance, I have produced two views, as shownI in Fig. I, which will clearly illustrate the generalsimilarity of ideas, covering a lapse of fifty-eightyears. Prof. Morse adopted the underground experiment, not knowing the disastrousfailures that had followed like attempts in Eng-land, and, strange as it may seem, the very workin this line in this country, to-day carries with itthe ear-marks of fifty years ago, and Morsesfirst cable was a bunch of five wires, lead en-cased. Prof. Morses first cable was laid fromBaltimore to the Relay House, seven miles dis-tant, and the failu
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