SKETCH OF ELI SB A GRAY. 523 



three cases caused by drinking-water a period of incubation of twenty- 

 one days. In our own epidemic one case occurred in fourteen days 

 after drinking the water, the average time being about twenty days. 

 The general experience at the present time points to an incubation of 

 about three weeks ; but it may vary from two to four weeks, or even 

 longer. 



It is an interesting question, but one to which I cannot give a 

 satisfactory answer, Why do not all who are exposed to the infecting 

 cause suffer from the disease ? In some cases it may be due to idiosyn- 

 crasy. Some people resist powerfully the encroachment of all infectious 

 diseases, while others seem fated to have an opportunity of testing in 

 their own person every prevailing malady. Experience teaches, how- 

 ever, that typhoid fever, unlike many other diseases of the group, is fa- 

 vored in its development by unhygienic surroundings. Bad air, bad 

 food, uncleanliness, and over-population of a house or quarter of a citv, 

 create a condition in the system favorable to a rapid and virulent de- 

 velopment of the fever after an infection by the germs. We know 

 nevertheless, that no house nor person is exempt from the disease after 

 receiving the exciting cause. Prince and peasant alike have to bow to 

 the malignant potency of these infecting germs. 



-♦♦♦- 



SKETCH OF ELISHA GKAY. 



By GEOEGE B. PEESCOTT. 



~rpLISHA GRx\Y, the inventor of the Speaking Telephone, was born 

 -L-^ at Barnesville, Belmont County, Ohio, August 2, 1835. During 

 his boyhood he was profoundly interested in all the phenomena of na- 

 ture, and had an intense desire, whenever he saw any manifestation of 

 physical force, to become acquainted with the secret of its operation. 

 Among all the phenomena throughout the domain of physics, nothing 

 took such hold upon his mind as that exhibited in the various effects 

 produced by the action of electricity, and he read whatever he could 

 find relating to this subject with the same eagerness and interest that 

 most boys would read "Robinson Crusoe" or the "Arabian Nights." 



While yet a boy he constructed a Morse register, all the parts of 

 which were made of wood, with the exception of the magnet, armature, 

 and embossing point in the end of the lever (which latter he made by 

 filing a nail down to a point). He had the magnet bent into a U-form 

 by a blacksmith, and then wound it with brass bell-wire, which was 

 insulated with strips of cotton cloth wrapped around it by hand. For 

 a battery he made use of a candy-jar, in which he placed coils of sheet 

 copper and zinc, with a solution of blue vitriol. With these materials 

 he succeeded in making a very good electro-magnet, which would sus- 



