On Diamagnetism and the Concentration of Energy. 403 



In those cases where steel diaphragms were employed, 

 there was always a notable induced current, even when the 

 reading of the magnetometer was zero. This was probably 

 due to a slight residual magnetization of the diaphragms. 



The results stated in this paper may serve to explain a 

 phenomenon which has seemed somewhat obscure. Frequent 

 attempts have been made to increase the efficiency of a 

 magneto-transmitter by polarizing the diaphragm as well as 

 the magnet ; a common way of doing this being to employ a 

 horseshoe-magnet, one leg of which is in contact with the 

 edge of the diaphragm, while the other, about which the coil 

 is wound, is placed in its usual position opposite the centre. 

 But as a general rule little or no gain has seemed to result 

 therefrom, so far as can be judged by the performance of 

 such instruments in actual practice. It is quite probable in 

 this case that the increased approach to saturation of the 

 diaphragm may have so great an effect as entirely to prevent 

 the expected improvement. 



It will also be seen from our results that an increase in the 

 thickness of the diaphragm of a magneto-transmitter tends to 

 allow of the use of a stronger magnet, and for a given ampli- 

 tude of vibration to produce a stronger current. But it must 

 be remembered, on the other hand, that the greater rigidity 

 of the thick diaphragm will diminish this range of vibration 

 under the action of the voice, a difficulty which may to a 

 certain extent be remedied by using a diaphragm of large 

 diameter. 



XLVIII. On Diamagnetism and the Concentration of Energy. 

 By J. Paeker, B.A.^ late Scholar of St. Jolin's College, 

 Cambridge* . 



MANY of the discoveries wdiich have been made in 

 Physical science in recent times may be classed under 

 two great heads — the principle of the Conservation of Energy 

 and Carnot's principle. These principles are closely related ; 

 the former being mainly an experimental conclusion, the latter 

 a deduction from the first by means of Carnot's axiom. It 

 follows, therefore, that whenever the principle of Energy ceases 

 to hold, Carnot's principle will fail at the same time, but that 

 the failure of Carnot's principle does not necessarily invalidate 

 the principle of Energy. 



Carnot's principle only holds when the material system which 

 we are considering is restricted to receiving or losing energy 

 from other systems in the forms of heat and mechanical work ; 



* Communicated by tlie Author. 

 2 D2 



