>^ ,^.\ 



122 C!^ farmers' and mechanics' journal. 



C, a Spring. 



D, D, a Knuckle Joint, or Perpetual Lever. 



E, a strong Spiral Spring. 



F, a Lever. 



G, a Rack. 



The mode of using it is as follows : When any substance is to 

 be held in the Vice, it is placed as usual between the Joint A, A» 

 The foot is then placed upon F, and the pressure, acting upon the 

 jointed lever, brings the side A, B, up to the other. A small plate 

 of iron is attached to the side of the lever F, which catches in the 

 rack G, and thus holds the Vice together as long as is necessary. 

 As the lever hangs loosely upon its pivot, a side-motion disengages 

 it from the rack. The spring E, raises the joint D, D, and the 

 spring C, throws open the jaws. 



The strength of the gripe is regulated by having the side A, B, 

 made circular and notches cut in, which admits the end of the 

 lever D, and which may be so moved as to make it longer or 

 shorter, and the power be thus changed to a greater or smaller ac- 

 cordingly. 



This Vice is cheaply and easily made ; is powerful, and is supe- 

 rior to the other kind, in the ease and quickness by which any 

 thing is fastened in it, or liberated from it — a slight movement of 

 the foot being sufficient for that purpose. They are made whole- 

 sale and retail by the inventor. 



JONES, ON JAPANNING AND VARNISIIING....N0. 6. 



On the. preparation and use of a Mastic Varnish, particularly suita' 

 hie for Paintings in Oil. 



TO THE editor. 



Sir, — Amateurs and collectors of paintings, are frequently at a 

 loss for a varnish properly prepared, and suited, for the purpose of 

 restoring and preserving the colors, in works of art. 1 submit the 

 following observations on the preparation of a very good one, and 

 the beat mode of appl}'ing it to the surface of pictures painted in 

 oil : 



Experience has shown, that for this purpose, mastic varnish is. 

 in general, preferaWe to any other, especially in the hands of in- 

 experienced persons, and, with but few exceptions, even in those 

 of the adept. This varnish is generally prepared by dissolving the 

 mastic in spirits of turpentine, over a sand heat, in a well-glazed 

 earthern, or in a copper vessel, occasionally shaking or stirring it 

 about, until entirely dissolved, which will take place before it ar- 

 rives at a boiling heat •, after which, it is strained through a piece 



