November 30, 1883.] 



SCIENCE. 



705 



disturbance, somewliat as one water-wave de- 

 pends on another ; for no one has ^-et been able 

 to trace one of our storms so far back as to 

 show it quite independent of previous storms, 

 as seems to be the case with the tropical 

 C3'clones. In the irregular blowing of the 

 winds of higher latitudes, for which no full 

 explanation can be given, too much air is 

 accumulated in certain districts, which then 

 appear as regions of high pressure. In seek- 

 ing a better l)alaiiced re-arrangement, surface- 

 currents are established with a rotar}- deflection, 

 as explained below, toward intermediate areas 

 of lower pressure ; and an up-draughtis formed 

 at their meeting. This becomes a storm-centre. 

 It might be said that friction would soon cause 

 all these local disturbances to cease, and atmos- 

 pheric pressure would then remain more uni- 

 form. So it might, if the air were drv ; but the 

 condensation of vapor, by which the cooling of 

 the ascending current is retarded, brings out a 

 new supply of energy eveiy time an up-current 

 is established ; and thus the disturbed condition 

 of the atmosphere is maintained. It cannot 

 settle down into a condition of equilibrium as 

 long as the sun shines, and water evaporates. 

 Some maintain that it is unlikely that the 

 storms of the torrid and temperate zones 

 should have different causes, and that as tem- 

 perate storms certainlj- do not, as a rule, arise 

 in a warm calm, tropical storms cannot have 

 such an origin. But as already stated, and as 

 will be further shown, the regions and seasons 

 of tropical cyclones point very conclusively to 

 this origin ; and, moreover, it is not necessary 

 that similar results should have identical 

 causes. All the peculiarities of a rotary storm 

 can be satisfactorily explained from either 

 starting-point. And the essential contrast 

 between the two cases is, that in one, ditfer- 

 ences of temperature precede and bring about 

 differences of pressure, and, in the other, dif- 

 ferences of pressure precede and bring about 

 differences of temperature ; so that, in both 

 cases, the established storm differs in tempera- 

 ture and pressure from the surrounding atmos- 

 phere : and, once established, the motions of 

 rotation and translation, yet to be described, 

 are closely alike in tiie two cases. 



( To be continued,) 



THE ELECTRIC LIGHT ON THE U. S. 

 FISH-COMMISSION STEAMER ALBA- 

 TROSS.^— Ml. 



To determine the efllciency of the system 

 of incandescent lamps, I measured, by means of 



' Concluded from Xo, 42. 



a steam-engine indicator, the power required 

 to run the engine and dynamo, the current 

 being switched off. By the same instrument I 

 measured tlic indicated power required to run 

 4.5, 50, and 70 lamps, respectiveh'. B3' de- 

 ducting from these experiments, respectivelj-, 

 ihe power required to run the engine aud dy- 

 namo, we obtained tlie power applied to the 

 shaft ; and from this quantity we deducted 

 the friction of the load, leaving, as a remain- 

 der, the net powers required to revolve the 

 armature in the magnetic field with lo, 50, 

 aud 70 lamps in circuit. The lamps used 

 were each of eight-candle power. 



Efficiency of the incandescent lamps. 



Horse-power required to run the engine and 



dynamo 5.3C 



Indicated liorso-power required to run 45 in- 

 candescent lamps ..... 5.79 



Indicated liorse-power required to run 50 in- 

 candescent lamps 5.85 



Indicated horse-power required to nm 70 in- 

 candescent lamps 6.92 



Net horse-power applied to the revolution of 

 the armature in tlie magnetic field, using 

 45 incandescent lamps .... 1.80 



Net horse-power applied to the revolution of 

 the armature in the magnetic field, using 

 50 incandescent lamps .... 1.85 



Net horse-power applied to the revolution of 

 tlie armature in the magnetic field, using 

 70 incandescent lamps .... 2.84 



Mean number of incandescent lamps per indi- 

 cated II. P.. using 45 lam*i)s . . . 7.77 



Mean number of incandescent lamps per indi- 

 cated H. P., using 50 lamps . . . 8.50 



Mean number of incandescent lamps per indi- 

 cated II.P., using 70 lamps . . . 10.11 



Mean number of incandescent lamps per net 



II.P., using 45 lamps 25, 



Mean number of incandescent lamps per net 



H.P., using 50 Lamps 27.02 



Mean number of incandescent lamps per net 



H.P., using 70 lamps 24.63 



The wires being fixed, their resistance may 

 be considered a constant quantity, and the 

 only variation as existing in the engine and 

 dynamo. Tlio distribution of the power, as 

 aliove recorded, may, if necessary, be verified 

 by electrical measurements on tlie wires. 



To illuminate the machinery on deck, the 

 dorrick-gafl', the lead of tlie cable, the trawl 

 as it comes on deck, and to afford an'iple light 

 to the naturalists while culling the contents of 

 the trawl as delivered on deck, an arc-light 

 of great power became indispensable. In the 

 tlien existing state of electric lighting, an ad- 

 ditional dynamo appeared to be imperative, as 

 no arc-light had been run from a tension of 

 51 volts. 



The Edison compan}-, however, was willing 

 to experiment, and in a short time produced a 



