SCIENCE, 



[Vol. VI., No. 126. 



The formative force, then, is a diffused ten- 

 denc3^ The very vagueness of the expression 

 serves to emphasize our ignorance concerning 

 the real nature of the force. In this connec- 

 tion, I venture to insist upon the fact that we 

 know little or nothing concerning any of the 

 fundamental properties of life, because I think 

 the lesson of our ignorance has not been 

 learned by biologists. We encounter not in- 

 frequently the assertion that life is nothing 

 but a series of physical phenomena ; or, on the 

 other hand, what is less fashionable science 

 just now, that life is due to a special vital 

 force. Such assertions are thoroughly unsci- 

 entific ; most of them are entirely, the remain- 

 der nearly worthless. Of what seem to me the 

 prerequisites to be fulfilled before a general 

 theor}^ of life is advanced, I have written else- 

 where.^ Charles S. Minot. 



UNDERGROUND WIRES. 



During the last few 3- ears the number of 

 electric wires in all of our lai-ge cities has rap- 

 idl}' increased, especially since the introduc- 

 tion of the telephone and the electric light ; 

 and the probabilit}^ is that the next few years 

 will show a further large increase. If these 

 wires run on poles, they not onl}' disfigure the 

 streets, but seriousl}^ interfere with the opera- 

 tions of firemen, as we have repeatedly seen 

 during the last few years. A cobweb of wires 

 supported on housetops requires the line-men 

 to continuall}^ tramp through the houses and 

 over the roofs, causing annoyance to the ten- 

 ants, and damage to the buildings. More- 

 over, wires fixed to housetops are subject to 

 removal at the whim of the owner, and the}^ 

 have to be continually removed from building 

 to building as the good will of each owner is 

 exhausted. Again: overhead wires, whether 

 placed on poles or housetops, are continually 

 coming in contact with each other, causing 

 annoyance and danger ; and an extra heavy 

 rain or sleet storm so entangles and breaks 

 them as to entirely interrupt communication. 

 The annual cost of repairs of overhead wires 

 in cities is not less than thirty' per cent of the 

 first cost of construction. 



In almost all of the large cities the question 

 is being asked. Why cannot these wires be 

 gathered into cables and buried, along with 

 the gas and water pipes, under the streets? 

 In answer, it is proposed to review briefly the 

 technical diflficulties that arise, and to show 

 how they may be and are overcome. It is 



1 C. S. Minot. On the conditions to be filled by a theory of 

 life. Proc. Amer. assoc. adv. sc, xxviii. 411. 



proposed, further, to compare the cost of con- 

 struction and maintenance of overhead wires 

 with the cost of construction and maintenance 

 of underground cables, and thus to see which 

 is desirable from economical considerations. 



There are two reasons, apart from the diflfl- 

 cxxMy of securing good insulation, why under- 

 ground lines are comparatively inefficient : — 



1. If an electric conductor be brought near 

 to a large mass of conducting-matter, as is a 

 wire when it is taken down from a pole and 

 buried in the earth, there appears in the cur- 

 rent the phenomenon of retardation, by which 

 each signal, instead of being sharp and dis- 

 tinct, is partly kept back, so that it overlaps 

 and mingles with the next. The result is to 

 limit the speed of working of the apparatus, 

 or, if, like the telephone, it be an apparatus in 

 which the currents are necessarily extremel}^ 

 frequent, to confuse and destroy the signals 

 altogether. 



2. The second diflSculty is called induction, 

 and is noticed when two or more wires are run 

 side \>y side and near together, as they neces- 

 sarily are in an underground cable. If the 

 signals on one wire of such a cable be sharp 

 and quick, they cause facsimile signals on all 

 of the neighboring wires ; and this, too, though 

 the insulation may be absolutely perfect. The 

 result of this phenomenon is, that messages 

 sent over one wire are liable to be received on 

 all of the other wires ; and in telephony each 

 person can easil}' overhear all that the others 

 are sa3ing. 



Fortunately, however, both of these difl3cul- 

 ties vary with the electrical qualities of the 

 cable ; and while I have seen cables of a thou- 

 sand feet, over which it was diflficult to talk, 

 and in which the cross-talk was nearly as loud 

 as the direct conversation, on the other hand, 

 I have conversed easily over an underground 

 cable extending from Paris to Orleans, eighty- 

 five miles ; and this, too, while other parties 

 similarly separated were talking over other 

 conductors of the same cable. There was 

 absolute secrec3^ 



Last summer I visited France and Germany, 

 and made, together with Mr. Berthon (chief 

 engineer of the French telephone company), 

 Mr. Gael (chief engineer of the French gov- 

 ernment telegraph) , and Herr Guillaume (con- 

 structor of the underground lines of the German 

 empire) , a series of telephone experiments on 

 underground lines, varying from 5 to 100 

 miles in length, from 2.87 to 48 ohms resist- 

 ance, and from 0.06 to 0.35 microfarads ca- 

 pacity per mile. 



These experiments furnish us with ample 



