IMPROVED SCREW-WRENCH. ()\ 



segment of a circle struck from the hinges on which it turns. 

 The perspective view in fig. 1 shows that this contrivance, 

 applied to any door, will not offend the eye, as it can 

 scarcely be distinguished from an ordinary door. K, fig. 1, 

 shows the -concave semicircle of the piece of wood fastened 

 to the doorcase, in which the semicircular end of the slip e 

 is to be received. 



XII. 



Description of an improved Screw-ivrench, to Jit different 

 sized Nuts, or Heads of Screws. By Mr. William Bar- 



SIR, 



JlT ERMIT me to make a few observations on a shifting 

 screw-wrench of my invention, which I beg leave to lay be- 

 fore the Society of Arts &c. through the hands of Mr. Bru- 

 nei, inventor of the block machinery here. 



I have found, from long experience, the imperfections °f Common 1 

 the various wrenches in common use, for the screw heads screw-wrench 

 and nuts of engines in general, which are often materially ecuve - 

 injured for want of an instrument that would fit variety of 

 sizes, and be applied with as much advantage as a solid 

 wrench. I have had it in view to unite steadiness with con- 

 veniency in making such an instrument, and flattering 

 myself that I have obtained both, I am desirous to com- 

 municate my invention to the Society, and have therefore 

 sent an instrument on the principle I have actually used, 

 and which has met with the approbation of my employers 

 and other persons. 



This wrench, by means of a nut and screw, is adjusted An impTore^ 

 with the greatest ease to the exact size required, and in that ^ rench « 

 state rendered so steady, that in use it is found equal to a 

 •olid wrench. 



* Trans, of the Society of Arts, vol. XXvj, p. 199. Five guineas 

 vere Toted to Mr. Barlow for this invention. 



I have 



