maintaining sixteen thousand lamps, even if only a fifth part would be in use at one time, and also for 3up|il}-ing power to small motors, is still in doubt. At present power ie not sup- plied. It was intended that the sj'stem should be nsLtl for supplying ^Kiwcr in the day-time, and light at night.
Leaving the central station in New York, Dr. Hagen then proceeds to inspect the village plant at Roaelle, N.J., and studies this new and promising development of electric light- ing, of which there are already several exam- ples in the United States, notably that at Brockton, Mass. At Roselle three so-called two- hundred -a nd-fifty-light machines are in- stalled, which ore driven by a thirty-five-horse power engine. The price is a dollar per thou- sand candle hours (kerzenstunde) . The elec- tromotive force of the machine is :i20 volts. and the current per lamp -j^ of an ampere. The number of lights in practical use is 800. The greatest distance to which the system is carried at present at Roselle is about 4,500 feet.
The writer then discusses the system of the U. S. electric-lighting company, which uses the Weston machine and the various modiGcations of the Maxim lamp, also the Bernstein elec- tric-lighting system. The author closes his interesting and valuable discussion of the va- rious systems of in candescent lighting by a risumi of the measui-ements made at Munich and at Paris, and an analysis of the cost of the FMison system. In this chapter will be found statements of the cost of this system from various agents of mills which are lighted by the incandescent hght. So many elements peculiar to each installation enter into this analysis, that it is impossible to say in general what the cost of electric lighting is. Each business-man must decide for himself whether it is economical, on the whole, for him to use the electric light or not. In many cases there is decided advant^ige, and even economy, in its employment.
Dr. Ilagen details in a graphic way the hopes raised by the ^'arious storage- batteries, and the leaden thoughts of those who have had their hopes dispelled. These batteries at present are useful only in laboratories.
The third portion of Dr. Hagen's treatise is devoted to arc-lighting, and in it the systems of Brush, of Weston, and of Thomson-Hous- ton, are fully described. The treatise closes with a short essay on the dangers of electric lighting, and a copy of the regulations adopted by the board of fire-insurance inspectors in Boston.
���NOTES AND NEWS.
Mb. Hbnky Loub of Rochester, N.Y„ ha* of- fered, throi^li the American public health auocla- tlon, Lhe luni of $2,800, to be awarded as Rrst and second (irises for pnpers on the following subjects: —
1°. Ueallby homes and foods for Lhe working- classes: Brst priiee, fSOO; second prixe, $200. Es- safa to be of a practical character, devoid, as far as poaaibte, of scienllflc terms. Tbe; must be within Ibe scope anil understanding of all classes, and de- signed especially for a popular work. 2". The sani- tary condltinni and necessities ot scboothousei and school -1 i Fe : first prize. $500; second prize, i 3°. Disinfection and Indlriduai prophylaxis agalnitf infectious diseases: first prize, tSOO; second price $200. i°. The preventable causes of disease, injur, and death, in American manufactories and worh^ shops, and the best means and appliances tor prft venting anil avoiding them: first prize, $500; secoiM prize, $200.
All essays written for the above priMs must be till the hands of llie secretATy. Dr. Irving A. Watson, Concord, N.H., on or before Oct. 16, J8S5. U is ex- pected that arrangements can be mode to have these essays widely distributed to the public, and to the persons most interested in the respective aubjecLi in the United Slates. The American public health association eamestij appeals to those able to com- pete, to take part in this work, which, it is believed, will do much to augment the health, comfort, and happiness of the people.
— In addition to the Issue of its regular publica tions, the Leaader MoCormick observatory of tha Unlverslly of Virginia (Professor Ormond Stone, di- rector) has begun the issue of a series of circulars, of which the number just received contains the ele- ments and epbemeris of tbesmall placet Barbara No. £U. Tbe elements and perturbations by Jupiter were computed by Mr, S. M. Barton; and the pertur> bationa by Saturn and lhe epbemeris, by Mr. P. P. Leavenworth.
— Tbe quinquennial prize offered by the lielgiai government for researches in mathematical and physical science has been awarded to Professor Le Paige of the University of Li^ge, for his Investiga- tions in the higher geometry, and especially tor those relating to lines and aurfaces of the third \
— The valuable Cuben collection of Egyptian s tJquities, which has recently been acquired by Ibe Johns Hopkins university, will be of great Interest, not only Cor art, but for the historical study of the customs and laws of Egypt. It was begun in 1833 by Col. M. I. Cohen, during his travels in Egypt, aud consists of sis hundred and eighty-nine objects, procured mainly in the localities where they wei« originally discovered. A number of objects, how- ever, lielonged to the famous colleelion of Mr. Salt, her Majesty's consul in Egypt, which was sold in 1835. The collection consists chiefly of small works illustrating the history of the minor am hi E^pt,^
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