20 THE SEVEN FOLLIES OF SCIENCE 



is such that light, traveling at the rate we have named 

 (185,000 miles per second), would take millions of millions 

 of years to pass across it, and let us further suppose that 

 we know the diameter of this mighty space with perfect 

 accuracy ; then, using Mr. Shanks' 707 places of decimal 

 fractions, we could calculate the circumference to such a 

 degree of accuracy that the error would not be visible under 

 any microscope now made. 



An illustration which may impress some minds even 

 more forcibly than either of those which we have just 

 given, is as follows : 



Let us suppose that in some titanic iron-works a steel 

 armor-plate had been forged, perfectly circular in shape 

 and having a diameter of exactly 185,000,000 miles, or 

 very nearly that of the orbit of the earth, and a thickness 

 of 8000 miles, or about that of the diameter of the earth. 

 Let us further assume that, owing to the attraction of some 

 immense stellar body, this huge mass has what we would 

 call a weight corresponding to that which a plate of the 

 same material would have at the surface of the earth, and 

 let it be required to calculate the length of the side of a 

 square plate of the same material and thickness and which 

 shall be exactly equal to the circular plate. 



Using the 707 places of figures of Mr. Shanks, the length 

 of the required side could be calculated so accurately that 

 the difference in weight between the two plates (the circle 

 and the square) would not be sufficient to turn the scale of 

 the most delicate chemical balance ever constructed. 



Of course in assuming the necessary conditions, we are 

 obliged to leave out of consideration all those more refined 

 details which would embarrass us in similar calculations on 

 the small scale and confine ourselves to the purely mathe- 



