332 



SCIENCE. 



[Vol. XIII. No. 326 



sixteen-foot cars. By aid of this device the batteries are changed 

 in less than three minutes. In actual time, less than five minutes 

 are required to inspect the car thoroughly and change the battery. 



A feature of this system is, that a street-railway need no longer 

 have its own generating machinery, as must be the case with ca- 

 bles, overhead wires, and conduit systems. In every town and city 

 where there is a central lighting-station, power for charging the 

 batteries, it is stated, may be purchased for about two cents per 

 horse-power ; so that the plant of the system will be reduced to the 

 devices of one battery-rack, as above described, for each set of 

 fifteen cars, and switch-boards for governing the distribution of the 

 current. 



The cost of motive power for a car-day of 60 miles, the com- 

 pany estimate at $3.10. By motive power, they mean cost of 

 energy at two cents per horse-power, and $700 per annum for 

 maintenance of batteries and motor. These figures, they claim, 

 are the result of their present e.xperience. To those who may 

 think two cents per horse-power a low estimate, they say that they 

 have offers from electric companies to furnish power at that figure. 



scratch or dull when touched. The varnish is mainly intended, of 

 course, for " ivory " film negatives, and for this purpose nothing 

 can be better. It will not crack or soften ; dust, water, and 

 foreign matter will not adhere to it ; and retouching is facilitated 

 by its use. 



THE JULL SNOW-EXCAVATOR. 



In December last the JuU Snow-Excavator Company sent out a 

 preliminary circular, calling the attention of railroad officials to the 

 fact that its snow-excavator was in course of construction, under 

 recent patents of Mr. Orange JuU of Ontario, Canada. Since then 

 the excavator has been completed, and submitted to three severe 

 tests on the Rome, Watertown, and Ogdensburg Railroad at Os- 

 wego, N.Y. 



On March 6, 1889, the excavator cleared seven hundred and fifty 

 feet of track, covered with hard frozen snow varying in depth from 

 two to seven feet. The snow was thrown a distance of sixty feet. 

 This was a particularly severe test, by reason of the fact that the 

 snow had been lying upon the siding during the entire winter, and 



JULL SNOW-EXCAVATOR, WITH HOOD REMOVED. 



The new cars, thirty of which are now under construction by 

 the Stephenson Company, will weigh but a fraction over six tons ; 

 or, in other words, but little more than the cars of the overhead 

 system. 



IVORY VARNISH. 

 A NEW medium for protecting glass negatives and positives 

 from injury by dampness, friction, or moist printing-paper, has re- 

 cently been introduced under the name of " ivory varnish," accord- 

 ing to The Photogt'aphic Times ; and, so far as experiments with 

 it have progressed, it seems to be an excellent and safe compound. 

 As it dissolves pyroxiline, however, it cannot be used for collodion 

 plates ; but it is perfectly applicable to gelatine negatives. The 

 latter need not even be heated when the varnish is applied, but the 

 preparation is merely flowed over their surface and dried in an 

 ordinary temperature. The result is a protective film of extreme 

 hardness, which perfectly resists the action of all moisture. A 

 negative thus varnished, after being thoroughly dried, may be im- 

 mersed in hot water of 120° F., and wiped dry with a rag, without 

 injury. This quality makes the " ivory varnish " an excellent one 

 for transferred bromide prints. The damar varnish heretofore 

 used for this purpose, being softened by a high temperature, will 



was nearly as hard as solid ice. Some of the pieces of ice thrown 

 out were afterwards weighed, and one was found which weighed 

 seventy-five pounds. 



On March 9, 1889, the excavator cleared a siding upward of nine 

 hundred feet in length, filled with hard snow varying in depth 

 from two to eight feet. The time consumed was not taken on 

 either of the above occasions ; but the excavator worked steadily, 

 and without any stoppage whatever. 



On March 11, 1889, the third exhibition was made at Oswego. 

 This demonstration was witnessed by representatives of the Rome, 

 Watertown, and Ogdensburg Railroad, the Lehigh Valley Railroad, 

 and the Pennsylvania Railroad. In this case the excavator was 

 timed, and exact measurements taken, by the railroad officials 

 present, of the length of the cut, and depth of snow. The length 

 of the cut was 720 feet ; average depth of snow, 7 feet, varying in 

 depth from 18 inches to 10 feet or more; the width of space 

 cleared was 10 feet. This cut was cleared of snow, and the rails 

 left clean, without the use of flangers, in seven minutes time. The 

 motive power was furnished by two passenger-locomotives, one 

 with a cylinder 16 by 22, and the other 17 by 24. The number of 

 revolutions of the bladed cone did not exceed 180 per minute, al- 

 though its capacity exceeds 300 revolutions per minute. Thus it 



