456 Description of an Improved Screw Wrench 



slip is cut into a segment of a circle struck from the binge* 

 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 d.stinguished from an ordinary 

 door. A", fig. J, shows the concave semicircle of the piece 

 of wood fastened to the door-case, in which the semicircular- 

 end of the slip e is to be received. 



**=SF 



7 



LXXX. Description of an Improved Screw Wrench to fit 

 different -shed Nuts or H^ads of Screws. By Mr. Wm. 

 Barlow, of His Majesty s Dock Yard, Portsmouth*. 



p S,R ' 



XTermit me to make a few observations on a shifting screw? 

 wrench of my invention, wfjich I beg leave to lay before the. 

 Society of Arts, &c, through the hands of Mr. Brunei, 

 inventor of the block machinery here. 



I have found, from long experience, the imperfections of 

 the various wrenches in common use, for the screw heads 

 and nuts of engines in general, which are often materially^ 

 injured for want of an instrument which 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 my- 

 self that I have obtained both, I am desirous to communi- 

 cate my invention to the Society, and have therefore sent, 

 an instrument on the principle I have actually used, and; 

 w.hich.has met with the approbation of my employers and, 

 other persons. 



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

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

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

 3olid wrench. r .J,l^ 



• I have> for several years, been intrusted with the care 

 and. repairs of many valuable engines of various descriptions,. 



* "From Transactions of the Society for the Encouragement of Arts, Mami- 

 fdcture^, and Commerce, for 1808.— i — Five guineas were voted to Mr. Barlow 

 for this commuflkatioa. . •" '• 



ll ,* . . • . ^ * : 'composing 



