SCIENCE. 



[N. B. Vol. XV. No. 390. 



whicli 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 arti- 

 cles 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 cheap- 

 ness of cost which would have been re- 

 garded as quite unattainable by the found- 

 ers, for example, of the New York Academy 

 of Sciences. The ready availability of, and 

 the constant demand for, all these 

 products to meet the daily needs of the 

 complex civilization of our time affords a 

 sufficient answer to him who would ques- 

 tion the efforts spent in attaining those 

 products or the efforts applied in subject- 

 ing new objects of study to the rigorous 

 tests of measurement and calculation. 



But the principles of measurement and 

 calculation are not limited in their appli- 

 cation to external objects, or to the prop- 

 erties of what we are sometimes pleased to 

 call 'gross matter.' They apply equally 

 aptly in many ways to man himself, and it 

 is clear that with advancing civilization we 

 may confidently expect such application to 

 be greatly extended. While we have not 

 yet attained formulas Avhich will compre- 

 hend the vagaries of the individual, we 

 have many formulas which will accurately 

 express the resultant of those vagaries as 

 manifested in racial types. A life insur- 

 ance company, for example, may not assert 



at the beginning of a year that any indi- 

 vidual of ten thousand men of the same 

 class will die within the year, but it may 

 assert with practical certainty that a 

 definite number of this class will die within 

 the year. Such 'facts and figures' are trite 

 enough, of course, but what we commonly 

 fail to see and appreciate is the solid basis 

 on which they rest, and how greatly it 

 would be to our advantage to extend the 

 •same sort of reasoning that has built up 

 great systems of fire and life insurance 

 into other departments of human affairs. 

 Most people, I fear we must infer, are, 

 like Thomas Carlyle, still scoffers at statis- 

 tics, and few, even of the educated, have 

 any adequate conception of the order which 

 the principles of probability will bring out 

 of the apparent disorder of statistical 

 data. 



Of the larger objects of the universe to 

 which measurement and calculation have 

 been applied with success, the earth easily 

 surpasses all others in interest and impor- 

 tance. So great has been this success that 

 one may assert that we know more of the 

 earth than we do of any other body to 

 which science has given attention. Its 

 size, its shape, the amount and arrangement 

 of its mass, its magnetic properties, its 

 speeds of rotation and translation, its 

 precession and nutation, and the lately dis- 

 covered wabbling of its axis of rotation are 

 all known Avith a definiteness which is truly 

 surprising when one considers its magni- 

 tude and the degree of complexity of those 

 properties. That the eight thousand mile.'? 

 in its diameter should be known within a 

 few hundred feet, that the two hundred 

 millions of square miles in its surface 

 should be known within a few hundred 

 square miles, or that the acceleration of 

 gravity at any point on its surface should 

 be known within a few millimeters per 

 second per second, are results little short of 

 marvelous when one reflects that they have 



