THE ELECTRICAL EXHIBITION. 345 



system. Here is the joint exhibit of the Ordnance Corps and Signal Service of 

 the army, with its electric self-recording rain gauge, its model of a field telegraph 

 train and portable field telegraph apparatus, its instruments for measuring the 

 force and direction of the wind and the velocity of projectilies, and for determin- 

 ing barometric pressure, besides the familiar system of signaling. 



Hard by is the Navy Department's exhibit, which includes torpedoes fired 

 by electricity and others exploded by contact; electrical appliances for firing 

 guns separately or in broadside; a pair of revolving naval search hghts operated 

 by Gramme dynamos; electrical appliances for determining water currents or 

 electric currents; devices for exploding torpedoes in boats, and the ingenious 

 McEvoy apparatus for controlling a group of torpedoes from a common centre, 

 and above all, for ascertaining the presence of hostile torpedoes by a telephonic 

 detector sunk under the water, and communicating the news of their proximity 

 to the patrolling boat by a peculiar low sound. In one of the towers is a great 

 electric naval search light, perhaps the most powerful in the country, throwing its 

 ray, by means of lenses and reflectors, over the city for a distance of more than 

 two miles. 



Fire alarms and burglar alarms of many kinds — matting with electric wires 

 that can be put under carpets ; wires and bells that connect with doors, windows, 

 and safes; telephones in their now familiar guise, one of them communicating 

 even with Boston; photometers and telemeters; locomotive head-lights; arcand 

 incandescent lamps of all varieties ; electric clocks and electric apparatus for mi- 

 nutely subdividing time — these are encountered on every hand. The applications 

 of electricity to medicine, dentistry, and surgery find a place, as does educational 

 apparatus for the school room. There are the marvels also of the phonograph, 

 the microphone, and various devices used thus far mainly for entertainment. 

 The telegraph, too, has its share of attention after all in the exhibition of its mul- 

 tiplex system, which allows scores of messages to be sent simultaneously over the 

 same wire without the slightest interference or betrayal of each other — a most 

 useful invention in these days when the multitude of wires required under the 

 old system would be appalling. 



Electro-plating, lightning-rods with their copper wires and platinum tips, the 

 application of electricity to mining and blasting, and other familiar matters are 

 not neglected here. Groups of sewing-machines are at work on leather or on 

 cloth by the aid of electricity, and some of those who sew are merely doing on 

 exhibition what they have done in their own workshops for months. There is a 

 great case full of eggs, from which chickens are to be hatched by electricity. 

 Storage batteries of various sorts and exhibits of electrical supplies are found, and 

 many small dynamos seem adapted to almost any form of light sedentary labor 

 performed by man. A great variety of globes and chandeliers is shown, and 

 upholsterers and other tradesmen have taken advantage of this fact, it must be 

 confessed, to make displays of very beautiful wares, which no one would like to 

 miss seeing, though thier connection with the purpose of the exhibition seems 

 to be merely that of demonstrating that goods of their quality light up admirably 



