86 Sir John Robison on Cutting Curved-faced Files. 



Having thus noticed all the shocks of any severity which 

 are known to have occurred in Great Britain, during the 

 years 1839, 1840, and 1841, it may not be uninteresting to 

 record briefly the shocks felt during the same period in other 

 parts of the world. Data will thus be afforded for ascertain- 

 ing — (1.) Whether the shocks in this country occur at or 

 about the same time as those in foreign countries, — an opinion 

 very generally entertained ;* and (2.) Whether the shocks in 

 this country, present the same general features as those in 

 foreign countries. 



On Cutting Half-Bound, and other Curved-Faced Files. By the 

 late Sir John Robison, K.H., F.R.S.E., F.R.S.S.A. (Com- 

 municated by the Royal Scottish Society of Arts.)t 



It is well known to workmen that, although it be an easy 

 matter to get flat-faced files of almost any required degree of 

 smoothness and regularity of surface, a half-round file having 

 an approach to such smoothness or regularity is altogether 

 unattainable afc any cost. 



A method having occurred to me of striking half-round or 

 even round files with the same smoothness, and with nearly the 

 same accuracy of figure, as the flat files, I beg leave to sub- 

 mit the process to the Society, that it may, through these 

 means, become known to those to whom it may be of use. 



To form a half-round file, either convex or concave, I pro- 



* Mr Maclaren of Edinburgh has supported this view. Thus, with reference 

 to the earthquake at Zante, on the 30th October 1840, he observes, '^ Here we 

 have again a remarkable example of the coincident occurrence of earthquakes in 

 distant parts of the world. The town of Zante has been ruined by a series of 

 terrific shocks between the 24th and 30th October ; and our paper of 31st Octo- 

 ber records a shock on the 26th of that month at Comrie. The distance between 

 these localities is nearly 1700 miles. The bearing is SE. and NW. It may be 

 remembered, that the great earthquake of 23d October 1839, was felt simultane- 

 ously at Comrie, in Piedmont, and at Reggio in Calabria, — that is, over a line 

 coinciding in direction with the present, and only a little shorter. If we prolong 

 the line connecting Reggio and Comrie, farther north, it strikes Mount Hecla^ 

 and may thus be said to have an active volcano at each extremity — Etna at the 

 one and Hecla at the other. It is extremely probable, that we shall hear of 

 earthquakes, between the 24th and 30th October, in the Alps or Apennines, or 

 at other intermediate localities." — (Scotsman of December 1840.) 



t Read before the Society, 12th December 1842. 



