March i8, 1880] 



NATURE 



483 



works, which lead up to the conclusion that, in constructing such 

 machines on the shunt principle, the resistance on the rotating 

 helix has to be considerably reduced by increasing the thickness 

 of the wire employed, and that on the magnets has to be 

 increased more than tenfold, not by the employment of thin 

 wire, but by augmenting the length and weight of coil wire 

 employed. We reproduce two of these diagrams, No. I referring 

 to the old form of winding and No. 2 to the new. 



The results of this mode of distributing the resistances is sum- 

 marised as follows : — 



i. That the electromotive force, instead of diminishing with 

 increased resistance, increases at hrst rapidly, and then more 

 slowly towards an asymptote. 



2. That the current in the outer circuit is actually greater for a 

 unit and a half resistance than for one unit. 



3. With an external resistance of one unit, which is about 

 equivalent to an electric arc, when thirty or forty webers are 

 passing through it, 2'44 hor>e-po«er is l\\ ended, of which r29 

 horse-power is usefully employed, proving an efficiency of 53 

 per cent., as compared with 45 per cent, in the case of the 

 ordinary dynamo machine. 



4. That the maximum energy whidi can be demanded from 

 the engine is 2"6 horse-power, so that but a small margin of 

 power is needed to suffice for the greatest possible requirement. 



5. That the maximum energy which can lie injuriously trans- 

 ferred into heat in the machine itself is 1*3 horse-power, so that 

 there is no fear here of destroying the insulation of the helix by 

 exces ive heating. 



6. That ihe maximum current is approximately that which 

 would be habitually used, and which the commutator and collecting 

 brushes are quiie capable of transmitting. 



Hence the author concludes that the new machine will give a 

 steadier light than the old one with greater average economy of 

 power, that it will be less liable to derangement, and may be 

 driven without variation of speed by a smaller engine; also that 

 the new machine is free from all objection when used for the 

 para ise of electro-deposition. 



This construction of machine enables the author to effect an 

 important simplification of the regulator to work electric lamps, 

 enabling him to dispense with all wheel and clockwork in the 

 arrangement. The two carbons being pushed onward by- 

 gravity or spring power, are checked laterally by a pointed 

 metallic abutment situated at such a distance from the arc 

 itself, that the heat is only just sufficient to cause the gradual 

 wasting away of the carbon in contact with atmospheric air. 

 The carbon holders are connected to the iron core of a .solenoid 

 coil, of a resistance equal to about fifty times that of the arc, the 

 ends of which coil are connected to the two electrodes respec- 

 tively. The weight of the core (which may be varied), deter- 

 mines the force of current that has to [ass through the regulating 

 coil in order to keep the weight in suspension, and this in its 

 turn is dependent upon the resistance of the arc. The result is 

 that the length of the arc is regulated automatically, so as to 

 maintain a uniform resistance signifying a uniform development 

 of light. 



Linnean Society, March 4. — rrof. Allman, F.H.S.. 1 re- 

 sident, in the chair. — Mr. Middlelon exhibited two si ulls of 

 Babirwsa al/utus, Less., from Borneo, which though quite 

 adult, were both distinguished by unusual smallness of their 

 tusks. — Dr. A. Giinther brought forward two d< 

 obtained during the Challenger expedition [Echiodon 1 nd 

 Scope/us) to illustrate two kinds of metameric organs, first 

 dc-cibed by Ilr. Ussow, which lie described and design] 

 the lenticular and glandular kinds. Whilst admitting tl e 

 morphological resemblance of the farmer to an e\e, he (Dr. 

 Gunther) vjave reasons which induce him to di-sent from the view 

 that they are organs of vision. He showed that their structure 

 is not opposed to the view that they, like the glandular kind, 

 are producers of light, and that probably this production ol 

 or luminosity i- subject to the will of the fish.— Mr. J. Jenner 

 Weir, on behalf of Mr. Edw. A. Nevill, showed the stuffed 

 of a Prongbuck (Antiloeapra americana), shot by the latter in 

 the Rocky Mountains, An On the media 



region of hi specimen, what ap| cared to b- a short unbi arched 

 third bo'ii was developed. On discussion of ihe abnormality, it 

 was suggested it might rather be an elongated warty growth than 

 a true horn, after the type of the rear ..lies. A further careful 

 examinatlo into its structural conditions was recommended. — Mr. 

 E. Morell Holmes read a paper on Codiolnm gregarium, A. P.raun, 

 a. new Uritish alga discovered at Teignmouth by the Rev. K. 

 Cresswell. The author considers that the hypnospores described 



by Braun do not belong to Codiolum, but to another alga, usually 

 found growing w ith it. The growth of the plant and its fructi- 

 fication, contrary to Braun's supposition, last through the winter 

 and spring. Mr. Holmes also exhibited specimens of the fructi- 

 fication of Cheetopteris plumosa found in Britain for the first 

 time by G. W. Traill, of Edinburgh. The unilocular sporangia 

 in this instance were in a more advanced stage than those figured 

 by Areschoug, and the multilocular sporangia differed in character 

 froai the illustration given by the last-mentioned Swedish 

 naturalist. — Dr. Francis Day briefly rcc( unted the peculiarities 

 and descanted on the geographical distribution of a specimen of 

 the Hebridal Argentine ccught near the island of Skye, October, 

 1879. This fish has very rarely hitherto been got in the British 

 waters. It is more often met with on the Norway coast, but its 

 range extends southwards as far as the Mediterranean. It is 

 ed to frequent great depths and not to enter fresh water. 

 A fish has been obtained in New Zealand, Argentina decagon, 

 which seemingly quite corresponds with the foregoing, and it 

 will be interesting hereafter, on further examination, to ascertain 

 if they really are identical. — The following gentlemen were 

 elected Fellows of the Society : — Messrs. S. M. Bairstow, J. T. 

 Carrington, R. M. Middleton, S. O. Ridley, T. Charters-White, 

 and Prof. P. Martin Duncan. 



Mathematical Society, March 1 1.— C. W. Merrifield, I.R.S., 

 president, in the chair. — Mr. W. J. Curran Sharp was admitted 

 into the Society, and the following gentlemen elected Members : 

 — Mr. C. S. Peirce, Johns Hopkins University, Baltimore, Mr. 

 Emory McClintock, Milwaukie, Illinois, Prof. Seitz, Kirksville, 

 Missouri, and Mr. E. T emperley, M.A. — The following commu- 

 nications were mode to the Society : — Notes on a general method 

 of solving partial differential equations of the first order with 

 several dependent variables, by Mr. Tanner. — Note on the 

 integral solution of x" - 2 Py- = - 2 s or ± 2 z- in certain cases, 

 by Mr. S. Roberts, F.K.S. — Notes (1) on a geometrical form of 

 Landen's theorem with regard to a hyperbolic arc ; (2) on a class 

 of closed ovals who-e arcs possess the same property as two 

 Fagnanian arcs of an ellipse, by Mr. J. Griffiths. 



Anthropological Institute, March 9. — Francis Galton, 

 F.K.S., vice-president, in the chair. — The election of Mr. 

 George Morrison as a new member was announced. — Mr. Francis 

 Galton described the curious psychological fact of Visualised 

 Numerals, on which he wrote a preliminary memoir in NATURE, 

 vol. xxi. p. 252. This paper we hope to publish in our next 

 number. 



Dublin 



Royal Dublin Society, January 19. — Physical and Expeii- 

 mental Science Section. — Howard Grubb, M.E., in the chair. — 

 Note on the conductivity of tourmaline, by G. F. Fitzgerald, 

 F.T.C.D. The author pointed out that though tourmaline did not 

 possess unilateral conductivity for currents of uniform intensity, it 

 mieht for currents of variable intensity, and that the latter was the 

 true analogue of its unilateral heat conductivity. — Note on the 

 construction of guard-ring electrometers, by G. F. Fitzgerald, 

 F.T.C.D. In this paper the author shows the importance of 

 having both the trap-door and guard-ring constructed of the 

 same metal in order to insure a uniform di-tribution of electricity. 

 — On the theory of the loud-speaking telephone, by Prof. \\ . F. 

 Barrett. The author expressed his doubts as to the accuracy of 

 the received theory which attributes the diminution of friction 

 that occurs on the passage of a current to electrolytic action, a 

 film of "as being thereby produced, and hence a reduction of the 

 normal "stiction " between the chalk cylinder and the platinum 

 faced arm which vibrates the diaphragm. One object] in to 

 ;his theory is the enormous rapidity of the changes that must 

 occur and the difficulty of conceiving how the film of gas is to be 

 got rid of, even if produced in an infinitesimal portion of time. 

 Moreover, the author showed that even when the chalk was dry, 

 in the ordinary acceptation of the word, the action still took 

 place, excellent speaking being obtained from a cylinder that had 

 been exposed for a month to a highly heated room and not once 

 touched with water since it had been in the author's possession ; 

 doubtless if the chalk were strongly heated, its insulation would 

 be too great and the current would not pass. The tendency of a 

 closed electric current is to enlarge itself, and it might be to this 

 cause the phenomenon was due. But the electrodynamic action 

 of the current should occur equally well between a metal cylinder 

 bearing on the metal arm ; the author had therefore replaced the 

 chalk cylinder by a polished bras cylinder, and employing a 

 microphone transmitter at the other end of the line, the ticking 

 of a watch was perfectly well heard as soon as the brass cylinder 



