ruF. i.oAi^rn sin.M.ih'ixr. rr.rr.CK.ii'if c.ini.r. .157 



or api>r<>xiniatt'ly mu'-twi'iilii'lli iImI of ilu- pt-rtn.illoy t.ipc nf tlu' 

 New York-Azori-s cal>li-. 



1'ki)HI.i:ms I'.st ointisKici) 



Tlu- |)ri)|)(i>.il Id um' |Hrm.illi)\ liLuliii^ lo iiii rciM- tin- -.pct-d uf 

 li)HK tflt-nraph cal)li's was <>iu' outronu' of an in\ isti^;ation under- 

 takt'ii liy the author soon after the war to determine whetlier some of 

 the new melho<ls and materials deveh)ped primarily for telejjhony 

 mijjht not find important application to siihmarine lele^jraphy. In 

 the sul)se(iiient de\eiopment of the permalio>- loaded cable a large 

 number of new problems, both theoretical and practical, had to be 

 solved iK'fore the manufacture of a cable for a commercial project 

 could be uniiertaken with reasonable assurance of success. The 

 problems encountered were of three principal kinds. First was that 

 of the transmission of signals over a cable having the characteristics 

 of the trial conductors made in the laboratory. Although the theory 

 of transmission o\er a loaded cable had been prexiously treated by 

 others, the problem considered had been that of an ideal loaded cable 

 with simple assumptions as to its electrical constants and without 

 regard to the practical limitations of a real cable. The second class 

 of problems had to do with the practical aspects of design, manu- 

 facture and installation. In this connection an extensive series of 

 exiHTiments was conducted to determine the means required to 

 secure at the ocean bottom the characteristics of the laboratory 

 samples on which the transmission studies were based. Among the 

 numerous problems which arose in this connection were those con- 

 cerned with protecting the copper conductor from any possible dam- 

 age in the heat-treating operation which was necessary to secure the 

 desired magnetic characteristics, and those concerned with protecting 

 the strain-sensitive permalloy tape from being damaged by sub- 

 merging the cable to a great depth. The third class of problem had 

 to do with terminal apparatus and methods of operation. The 

 prospective speed of the new cable was ciuite bcyonti the capabilities 

 of standard cable equipment and accordingly new apparatus and 

 operating methods suited to the loaded cable had to be worked out. 

 In particular it was necessary to develop and construct instruments 

 which could l)e used to demonstrate that the speed which had been 

 predicted could actually be secured. The success of the investiga- 

 tions along all three lines is attested by the results which were ob- 

 tained with the New York-Azores cable. lig. 2 shows a section of 

 cable recorfler slip, the easily legible message of which was sent from 



