n MAKVELS OF POND-LIFE. 



curacy of definition, not increase of bulk, is the 

 great thing needful. 



Scientific men always compute the apparent en- 

 largement of the object by one dimension only. 

 Thus, supposing an object one-hundredth of an inch 

 square wei'e magnified so as to appear one inch 

 square, it would, in scientific parlance, be magnified 

 "one hundred diameters," or one hundred linear; and 

 the figures lOU would be appended to nny drawing 

 whicli miglit be made from it. It is, however, 

 obvious that the length is magnified as well as the 

 breadtli ; and hence the magnification of the whole 

 surlace, in the instance specified, would be one 

 hundi-ed tiuies one hundred,' or ten thousand ; and 

 this is the way in which mngtiification is popularly 

 stated. A few moments' consideration will shew 

 that the scientific method is that Avhich most 

 readily affords information. Any one can instantly 

 comprehend the fact of an object being made to 

 look ten . times its real lengtli ; l)ut if told that 

 it is magnified a hundred times, he does not know 

 what this reallv means, until he has sjone through 

 the j)rocess of finding the square root of a hun- 

 dred, and learnt that a hundredfold magnification 

 means a tenfold magnification of each superficial 

 dimension. If told, for example, that a hair is 

 magnified six hundred diameters, the knowledge is 

 at once conveved that it looks six hundred times 



