MATHEMATICS AND NATURAL PHILOSOPHY. 453 



the thermo-electric qualities in this direction differ from those in lines perpendi- 

 cular to it as antimony differs from bismuth ; that the reverse statement applies to 

 iron hardened by traction in one direction ; and that in each case the thermo- 

 electric quality of soft iron is intermediate to the two differing states. 



Again, in soft iron under magnetic force, and in that permanently magnetised 

 after the removal of the magnetising force, directions along the hues of magnetisa- 

 tion deviate thermo- electrically towards antimony, while those perpendicularly 

 across the lines of magnetisation deviate towards bismuth, from the unmaguetised 

 metal. Thus if a riband of iron, magnetised at an angle of 45° to its length, be 

 heated along one edge while the other is kept cool, when the two ends, kept at 

 the same temperature are put in communication with the electrodes of a galvano- 

 meter, a powerful current is indicated, in such a direction that, if pursued along a 

 rectangular zigzag from edge to edge through the band, the course is always from 

 across to along the lines of magnetisation through the hot edge, and from along to 

 across the same lines through the cold edge. (4) Various experiments were 

 made to detect the effects of certain influences on the electric conductivities of 

 metals. For instance, longitudinal magnetisation diminishes the conducting 

 quality of iron wire, and its electric conductivity is greater across than along 

 lines of magnetisation ; also, by magnetisation across the lines of electric current, 

 iron gains in conducting power, whence it is inferred that there is a certain direc- 

 tion, oblique to the lines of magnetisation, along which the conductivity of magne- 

 tised iron would remain the same on a cessation of the magnetising force. 



ON THE TEMPERATURE AT TORONTO. 



In the Phil. Mag., Nov., 1856, Mr. S. M. Drach points out that General Sabine's 

 formula (Phil. Trans., 1852) can be put approximately into the simple form — 



44°.23— 21°.81 sin a— 1°.06 cos 2a— 0°.80 cos 3«+0°.22 cos 4a— 0°.88 sin 5a 

 where a is the angle reckoned at 80° a mouth from October 24th, which is the 

 epoch of mean annual temperature. Hence he suggests that the meteorological 

 year should be taken from October to September inclusive. 



A NEW SPHTGMOSCOPE. BY DR. S. SCOTT ALISON, (PROC. L.S.) 



This instrument, designed for the purpose of indicating the movements of the 

 heart and blood-vessels, consists of ' a small chamber containing spirits of wine 

 or other liquid, provided with a thin india-rubber wall where it is to be applied 

 to the chest. This chamber communicates with a bent graduated tube which rises 

 to some height above the level of the chamber; liquid is supplied to the instru- 

 ment till it spreads in the tube a little above the level of the chamber. The 

 pressure of this liquid, acting on the elastic wall, causes it to protrude, and the 

 protruding part is very sensible to external impulse, yielding to the slightest 

 touch, and, being pushed inwards or returning outwards, causes a rise or fall of 

 the liquid in the tube, the amount and duration of which can be estimated with 

 much delicacy. By means of this instrument, Dr. Alison has detected two great 

 laws not hitherto known, namely, 'that the beat of the heart alternates with the 

 pulse of the wrist,' and, ' that the 1 pulse of arteries beyond the chest takes place 

 in all parts at the same instant, and without any appreciable interval.' " 



PHOTOGRAPHY. 



The attention of Photographers has been mainly directed of late to the perfect- 

 ing of some dry process by which the necessity of immediately using the wet 



