SCIENCE. 



[Vol. XI. No. 274 



that all the forms had about the same efficiency. The consump- 

 tion of oil is about 4.5 grams per candle-power per hour. 



Gas-Burners. 



Candle-F 



Mea 



ower. 



Cubic Feet per Candle-Power 

 per Hour, Mean. 











66 



40 

 181 



5 

 5 





Auer's incandescent 



Siemens regenerative No. 3 



" " No. I. . . 



WenhamNo.2 



No. 4 



.200 



.260 

 ■350 

 .230 



.160 



The argand burner is better than the fishtail : the latter uses nine 

 cubic feet per hour instead of five or six, as is usually calculated, 

 although this is largely a matter of local condition. The Auer in- 

 candescent lamp uses only half the gas that the fishtail consumes, 

 but the deterioration of the incandescent material must be added. 

 Of the high-candle-power lamps, the Wenham is most economical. 



Arc Lainps (Electric). 





Mean Candles. 



Mean Candles 

 per Horse-Power. 





250 

 820 



900 



T ,090 









Incandescent Lamps. 



Mag7iesium Lamps. 

 These consist of a small clock-work which gradually unrolls the 

 magnesium ribbon, and advances it through the centre of a reflector 

 at a rate which can be regulated to equal that of consumption. 

 From one to eight ribbons can be used. A ventilator is provided for 

 the escape of the fumes produced by the combustion of the metal. 



No. of Ribbons. 



Candles. 



Consumptio 

 per Ribbon for io< 



n per Hour 

 3-Candle Power. 



I 



3,200 



1 1. 14 grams. 



= 



5,880 



14.10 





4 



8,000 



14.80 



" 



-6 



11,300 



14.15 





S 



17,000 



14.03 



" 



The price of the ribbon is nearly five dollars a pound, and this 

 will make the price of one hundred candles per hour sixteen cents. 

 This lamp can be improved, and the price of magnesium will prob- 

 ably fall. 



A New Electric Meter. — Prof. R. Boernstein of Berlin has 

 invented a new form of current-meter for measuring the amount of 



current used at points of consumption. It consists of a compact 

 electro-dynamometer whose indications are proportional to the in- 

 tensity of the current, combined with a planimeter for integrating 

 the deflections. The registering-apparatus is attached to a vertical 

 wheel, which turns by the friction of a horizontal wheel driven 

 uniformly by clock-work, which it touches. As the vertical wheel is 

 nearer to or farther from the centre of the horizontal wheel, its 

 velocity of rotation is less or greater, and its position is governed 

 by the deflection of the dynamometer, being nearer the centre for a 

 small, farther for a large, deflection. The apparatus is compact, 

 and is said to measure to one-half of one per cent : it can be used 

 for both direct and alternating currents. In case the necessity of 

 winding the clock-work were an objection, it would be easy to ac- 

 complish this by a small motor that would be thrown in circuit 

 when the spring was uncoiled to a certain amount. 



The RADI0GR.4PH. — M. Louis Oliver proposes, by an applica- 

 tion of Crooke's radiometers, to measure the total amount of light 

 falling upon the vanes, the record having reference both to the 

 time and intensity of the light. As the vanes of the radiometer 

 revolve, they make contact with a wheel, closing an electric circuit. 

 The wheel form of contact is adopted, as it offers very little resist- 

 ance to the motion of the vanes. The current closes a relay, bring- 

 ing into action a more powerful current, which moves the needle of 

 a step-by-step apparatus across a scale. If the instrument is con- 

 stant in its action, and fulfils the expectations of its inventor, it may 

 be useful for photometric purposes, measuring the number of rota- 

 tions in a given time. 



Storage-Batteries on the Brussels Tramways. — There 

 have been lately reports of the failure of the storage-batteries on 

 the tramway in Brussels that is experimenting with them. It is 

 said that the deterioration of the batteries has been as much as 

 seven cents per car-mile ; and at that price they cost more than 

 horses. The company supplying the batteries has come forward 

 with the statement, that, since they delivered the cells, they have 

 never been consulted in any way, and that their directions have not 

 been complied with. It has been pointed out in this journal, that 

 while in many cases storage-batteries will to-day be cheaper than 

 horses, yet this will only be true when they are supplied at moder- 

 ate cost, and when the facilities and cost of renewal are reduced to 

 a minimum. At the same time, the cost of the batteries in Brus- 

 sels is more encouraging than otherwise ; for, at seven cents per 

 car-mile for depreciation, the cost will be only slightly greater than 

 that of horses, and the increased speed and comfort will more than 

 compensate for this. The total cost for horses may be roughly 

 estimated at ten cents per car-mUe for an ordinary car in our East- 

 ern cities. At seven cents for depreciation, the cost of batteries 

 will be something under eleven cents per car-mile. With the advan- 

 tages electricity offers, even this should throw the balance in its 

 favor ; and the calculation is on the most unfavorable data obtain- 

 able. 



The Eickemeyer Dynamo. — This dynamo dift'ers from the 

 ordinary type in that the field-magnet coils are wound close around 

 the armature, with a heavy shell of iron outside. The object is to 

 concentrate the lines of force where they are most needed, — 

 through the armature, — and to prevent magnetic leakage. It 

 makes a compact machine, which should give considerable output 

 for its weight. The principle of the ' ironclad dynamo,' such as is 

 embodied in Mr. Eickemeyer's invention, has been claimed by a 

 number of inventors. Whether Mr. Eickemeyer was the first to 

 construct such a machine or not, he seems the first one who has 

 made it a practical success. 



An Improved Prony Brake. — In an ordinary Prony brake, 

 in which the work of a machine is absorbed by the friction of its 

 pulley between two clamps fitting over it, and where the power is 

 calculated from the moment of the force tending to turn the 

 clamps, and the revolutions of the pulley, there are many difficulties. 

 The friction between the clamps and the surface of the pulley varies 

 from different causes, — changes in lubrication, change of pressure 

 due to heating, etc., — and the readings are most irregular. M. 

 E. iSIeylan has described a new form of brake, simple of use and 

 construction, that will measure with considerable accuracy powers 



