52 MODERN SCIENCE READER 



pelled the plates will adhere together, so that by lifting the 

 upper one the lower will be lifted along with it, as if they 

 formed one plate." 



Whitworth was essentially a tool maker. No sooner had 

 he perfected the plane, with its immense effect upon Eng- 

 lish industry, than he attacked the screw. His system of 

 screws is now adopted all over the civilized world. Follow- 

 ing up his improvements, he recognized the necessity for a 

 more exact measuring machine than any then in existence, 

 and supplying this want he devised a machine which would 

 measure distinctly and practically to the 40,000th part of 

 an inch, and theoretically to the 1,000,000th. To show to 

 what exactness this was brought, we quote his own words 

 in an address at Manchester in 1857 : ' ' Here, ' ' said he, "is 

 an internal gauge having a cylindrical aperture 0-5770-inch 

 diameter, and here also are two solid cylinders, one 0-5769- 

 inch, and the other 0-5770-inch diameter. The latter is 

 0-0001 of an inch larger than the former, and fits tightly 

 in the internal gauge when both are clean and dry, while 

 the smaller 0-5769 gauge is so loose in it as not to appear 

 to fit at all. These gauges are finished with great care, 

 and are made true after being case-hardened. The effect 

 of applying a drop of fine oil to the surface of this gauge 

 is remarkable. It will be observed that the fit of the larger 

 cylinder becomes more easy, and that of the smaller more 

 tight. ... It is thus obvious to the eye and the touch that 

 the difference between these cylinders of one ten-thousandth 

 of an inch is an appreciable and important quantity, and 

 what is now required is a method which shall express 

 systematically and without confusion a scale applicable to 

 such minute differences of measurement." The Whit- 

 worth gauges have been adopted by the Government as 

 standards of measurement. 



The accuracy in mechanical processes rendered possible 

 by Whitworth 's inventions bore its first proof in a direction 

 which the inventor little expected. 



England was engaged in the Crimean war, and the En- 



