ELECTRIC LIGHTING. 309 



which will bear without fusion a heat l of 5,000 degrees 

 Fahrenheit. It would be unsafe, however, to assume that 

 this account is trustworthy, or to infer (as we might in the 

 case of almost any other inventor), that such being the 

 nature of his plan, it could lead to no result of practical 

 value. As has been well remarked by a contemporary 

 writer, whatever Edison's invention may be, * it is certain to 

 be something to command respect, even if it does not quite 

 come up to the glowing accounts which have reached us in 

 advance.' 



The following passage from one of these accounts, which 

 appeared in the ' New York Herald,' will be read with interest, 

 and may be accepted as trustworthy so far as it goes.' 



* The writer last night saw the invention in operation in 

 Mr. Edison's laboratory. The inventor was deep in ex- 

 perimental researches. What he called the apparatus con- 

 sisted of a small metal stand placed on the table. Sur- 

 rounding the light was a small glass globe. Near by was 

 a gas jet burning low. The Professor looked up from his 



1 My occasional use of the word ' heat ' where in scientific writing 



* temperature ' would be the word used, has exposed me to peevish, not 

 to say petulant comments from Professor P. G. Tait, who has denounced 

 half the mathematical world for using the word ' force,' in the sense 

 in which Newton used it, and has spoken of an eminent physicist as 

 one deserving universal execration and opprobrium for not explaining, 

 when speaking of work done against gravity, that terrestrial gravity 

 was meant, and not gravity on the sun, or Jupiter, or Mars, or anywhere 

 in the heavens above or in the earth beneath, but only at the earth's 

 surface. Where there is no risk of confusion, the word * heat ' may 

 be used either to signify temperature, as when in ordinary speech and 

 writing we talk of blood-heat, fever-heat, summer-heat, and so forth. 

 Science, indeed, very properly forbids the use of the word in any sense 

 save one. But outside the pages of scientific treatises, there is no 

 inaccuracy in using a word in a sense popularly attributed to it, when 

 no mistake can possibly arise. No one can suppose, when I speak 

 of a heat of so many degrees Fahrenheit or Centigrade, that I mean 

 anything but such and such a degree of heat, any more than if I 

 spoke of the intense heat of that savant entete, Professor P. G. Tait, any 

 one would imagine that I referred to his calorific condition. 



