126 ANNUAL OF SCIENTIFIC DISCOVERY. 



all our knowledge of the magnetic force. This anomalous result the author 

 traced to the assumption laying at the foundation of the present theory of 

 the intensity, viz., that the terrestrial force is exerted in the direction of the 

 dip; and from an analysis of the phenomena of the dip he arrived at the 

 following la\vs : 1. That the true direction in which the earth's force is ex- 

 erted is in the radial line of its centre, at least so within certain limits, the 

 earth being a spheroid and not a sphere. 2. That the force being at all 

 points upon the earth's surface exerted in the radial line of its centre, and 

 the vibrations of a horizontal needle being therefore, at all stations, made at 

 right angles to the direction of the force, their number at an}* two or more 

 stations in similar times, or at different periods in similar times, indicates 

 exactly the ratio of the force at each station and at each period. 



ON FLUORESCENCE PRODUCED BY THE AURORA. 



Mr. T. R. Robinson, of Armagh, in a letter to the Phil. Magazine, writes as 

 follows : On the occasion of an aurora of more than average brightness, on 

 the 14th of March, 18-38, I availed myself of the opportunity to try whether 

 this light was rich in those highly refrangible rays which produce fluorescence, 

 and which are so abundant in the light of the electric discharges ; and I 

 found it to be so. A drop of desulphate of quinine on a porcelain tablet 

 seemed like a luminous patch on a faint ground; and crystals of platino- 

 cyanide of potassium were so bright, that the label on the tube which con- 

 tained them (and which by lamplight could not be distinguished from the 

 salt at a little distance) seemed almost black by contrast. These effects were 

 so strong, in relation to the actual intensity of the light, that they appear to 

 afford an additional evidence of the electric origin of the phenomenon. 



RELATIONS OF MATTER AND FORCE. 



The late Dr. Samuel Brown, of Edinburgh, whose scientific essays have 

 recently been published, was one of the boldest and most original thinkers 

 among the scientists of the present century. His speculations concerning 

 ultimate connection of matter and force, as embodied in the following para- 

 graph, are especially worthy of notice. 



" A particle," he says, " is a molecular nucleus, surrounded by five polar 

 spheres of force; the first, that of repulsion, which is never overpassed in the 

 chemical, any more than the first repulsive sphere of the sun is in the astro- 

 nomical, operations of nature ; the second, that of proper chemical affinity ; 

 the third, that of repulsion, which hinders the compression of a solid body 

 by surrounding forces; the fourth, the attractive sphere . of solidiformity; and 

 the fifth, the repulsive sphere of gasiformity. It is called a molecular nucleus 

 to distinguish from both the point of infinite repulsion defined by Boscovich, 

 and the solid nucleus of Newton, and to indicate that the chemist has no more 

 to do with what is within his ultimate atoms than the astronomer with what 

 is within his stars. Nor is it meant that there are no more than five spheres of 

 force ; but only that the chemical atomician, contemplating matter under the 

 conditions of gasiformity, liquidity, solidity, and chemical combination, has 

 to consider these five alone. A particle of hydrogen, revolving like a planet 

 round oxygen on their outermost spheres of repulsion, produces the smallest 

 mass of these gases diffused by Dalton's law in the ratio of particle to par- 

 ticle; revolving round oxygen on the second outermost spheres of repulsion, 

 they should produce the smallest mass of an analogous solidiform substance, 



