May 26, 1899.] 



SCIENCE. 



r53 



Lehmanu's ; the two perhaps had the same 

 number-habit. Does Professor Titchener seri- 

 ously thiuk that a number-habit in a guesser 

 can account for the amount of coincidence be- 

 tween the numbers which he guesses and those 

 upon counters drawn at random out of a bag ? 

 Even in anti-telepathic Science accuracy of 

 representation is required, and I am pleading 

 not for telepathy, but only for accuracy. 



William James. 



on the wehnelt current breaker. 



To THE Editor of Science : The following 

 facts, noticed while experimenting with the 

 Wehnelt electrolytic current breaker, may be 

 not without interest : 



In order to test if the action of the breaker 

 could be due to a spheriodal state, produced 

 by the high temperature of the positive elec- 

 trode, some means for measuring the tempera- 

 ture of this electrode had to be obtained. 

 For this purpose I used electrodes of fusible 

 metals melting at different temperatures, the 

 temperature of the electrode being neces- 

 sarily less than that at which the alloy 

 melts, if the latter remain unfused. In this 

 way one can at least obtain the superior 

 limit for the temperature of the electrode. 

 Starting with a fusible alloy which melted 

 at about 78° C, the electrode melted as soon 

 as the circuit was closed. The nest metal 

 used melted at 96° C, and was fused an ap- 

 preciable, though very short, time after the cur- 

 rent was established. Finally, using an anode 

 made of a metal which melted at 168° C, no in- 

 dication of fusion of the electrode could be de- 

 tected, even after the breaker had run for ten 

 minutes at a time. This seems to show that 

 the temperature of the electrode was far below 

 200°, the temperature necessary, at atmos- 

 pheric pressure, for the production of the sphe- 

 roidal state. 



The influence of self-induction on the action 

 of the breaker was also studied, to some extent. 

 Diminution of the self-induction in circuit di- 

 minishes the period of the action, as is shown 

 by the heightened pitch of the sound produced. 

 But absence of all self-induction prevents wholly 

 the working of the breaker. The cell was used 

 in a circuit composed of a storage battery, non- 



inductive electrolytic resistances and wires 

 wound nou-inductively. With this arrange- 

 ment no interruption of the current could be 

 produced, though the electromotive force was 

 raised to thirty volts and the current to 

 eighteen amperes. As soon, however, as a coil 

 with self-induction was put in the circuit the 

 action of the breaker recommenced. Induction 

 in the circuit is essential to the action of this 

 form of interrupter. 



Howard McClenahan. 

 Physical Department, Princeton University. 



THEBMODYNAMIC ACTION OF 'STEAM-GAS.' 

 One of the most valuable papers recently 

 published in the fields of applied science is that 

 which has just been reprinted from the Beviiede 

 Mecanique of the last year, the work of Profes- 

 sor Sinigagalia, a well-known author in that 

 field.* 



This is the latest and, in many respects, the 

 most complete discussion of a supremely impor- 

 tant subject ; one to which the minds of men of 

 science and engineers the world over are now 

 again turning after a period of many years, 

 during which the thermodynamic promise of 

 gain in efficiency in the steam-engine through 

 the conversion of a vapor into a gas by this 

 process of superheating had been almost univer- 

 sally believed to be more than counterbalanced 

 by the very serious difficulties met in the earlier 

 days in the attempt to profit by it. Changes 

 have taken place during the last generation 

 which are now thought by many authorities to 

 have largely reduced the obstructions formerly 

 seemingly fatal to a great thermodynamic ad- 

 vance. 



In the practical thermodynamic operation of 

 the steam-engine, asM. Bertrand has remarked, 

 there is no such thing as ' saturated vapor, ' as 

 that term is customarily employed by the 

 thermodyuamists. The working fluid is always, 

 in fact, a mixture of vapor and its liquid, in a 



*Application de la Surchauffe aux Machines a Va- 

 peur par M. Franjois Sinigaglia, Professeur agr<5ge 

 des Ingenieurs de Naples ; Ingunienr-Directeur de 

 rAssociation des Propri6taires d'Appareils a Vapeur 

 dans les Province napolitaines. Extrait de la Bevue 

 de Mecanique (1897-98); Paris, V've Ch. Dunod, Edi- 

 teur, 1898. 



