32 RECORDS 



cules and atoms of gases. Recent investigations point to the 

 conclusion that there is another order of bodies of much smaller 

 dimensions and possessing still more wonderful properties. 

 These have been called corpuscles.^ Their density is only 

 about one thousandth as great as that of the lightest gas, hydro- 

 gen ; they are freely given off by several of the so-called radio- 

 active substances ; and they move about with speeds of the 

 same order as the velocity of light. It appears not improbable 

 that they play a most important role in cosmic as well as in ter- 

 restrial physics, and the amount of attention being given to 

 them justifies the hope that their study may illuminate many 

 obscure corners in the realm of molecular science. 



Passing per saltum from the smallest measurable and calcu- 

 lable quantities to those with which we have an every-day fa- 

 miliarity, I would direct your attention to the great number of 

 articles of commerce which are now weighed, measured and 

 rated with precision and sold at a cost which, a half century ago, 

 would have been thought quite impossible. Standard yards, 

 meters, pounds and kilograms, and pocket time-pieces that will 

 run within a few seconds per day, are available at prices within 

 the reach of all who need them. Screws and screw gauges 

 which will easily measure a hundredth of a millimeter (or four 

 ten-thousandths of an inch) are articles of trade ; beautifully 

 true spheres of steel or bronze may be had for a few cents each ; 

 helical springs of the finest steel and of remarkable uniformity 

 are sold for a dollar a dozen ; while articles like wire, tubing, 

 sheet metal, and an indefinite variety of tools and machinery are 

 made with a degree of perfection and at a cheapness of cost 

 which would have been regarded as quite unattainable by the 



1 See a paper by Professor J. J. Thomson, " On Bodies Smaller Than Atoms," 

 Popular Science Monthly, August, 1901. 



See also a paper by Professor John Cox on " Comets ' Tails, the Corona and the 

 Aurora Borealis," Popular Science Monthly, January, 1902. 



A fact of great interest in connection with the " corpuscles " considered in these 

 two papers is the repulsion of light impinging on bodies, the amount of which has 

 been actually measured recently by several observers. This repulsion between the 

 sun and the earth is very great, amounting to about a hundred million million dynes ; 

 but the gravitational attraction between these bodies is about forty million million 

 times as great as that repulsion. 



