126 ANNUAL OF SCIENTIFIC DISCOVEKY. 



movable jaw. Between and attached to these guide-pieces are a pair of cross 

 levers, or connecting rods, so pivoted and arranged that when the screw which 

 operates the vice is turned, the movable jaw will always retain a position ex- 

 actly perpendicular to that of the fixed jaw. All mechanics know the im- 

 portance of keeping the two jaws thus in agreement. It allows a firmer hold 

 to be taken on any substance placed between, relieves the screw of friction, 

 and prevents the tendency of the vice to become weakened or soon to wear 

 out. There are several different kinds of vices arranged with a view to ac- 

 complish the above purposes. The invention of Mr. Davis is intended to be 

 considerably cheaper in construction, and, if possible, more effective hi its 

 operations than any of them. Only one screw is employed and no nut is re- 

 quired to be sunk in the movable jaw. 



IMPROVED DOOR-LOCK, 



At the recent Fair of the American Institute Mr. W. H. Baxter of N. Y. 

 exhibited an improved door-lock, combining the safety of a bank-lock with 

 the simplicity of a latch-string. It opens from the inside by a simple pull on 

 the knob without straining or soiling the most delicate kid. On the street 

 side the key-hole is a narrow slit hardly large enough to admit a fine wire, 

 and the key is a small plate of thin metal thrust in directly without turning. 

 The end of the key is shaped into rectangular notches of unequal depth, and 

 presses upon six or more tumblers, each of which must be depressed to a 

 certain depth before " the bolt" will move. Strictly speaking, no bolt is em- 

 ployed in this lock, the fastening being made by a strong horizontal wheel of 

 small diameter, containing a large cavity, which embraces a corresponding 

 fixture in the door-fi<ame and holds on to it firmly. It is called the rotary 

 lock, and appears the strongest, the most easily operated with a key, and the 

 most difficult to work without that appendage of any we have ever examined. 

 The key is about the size and thickness of a two-shilling piece. New York 

 Tribune. 



IMPROVED BRICK MACHINE. 



At the Fair of the Eoyal Agricultural Society at Carlisle, England, a brick 

 machine involving some new principles was exhibited by Messrs. Porter & Co. 

 This machine, which was capable of turning out 18,000 bricks per hour, effects 

 the two processes of grinding and molding the clay simultaneously. The 

 grinding mill is horizontal, having two shafts, on which are placed two cylin- 

 ders, with a series of knives cast on each. It is fed with tempered clay, which 

 it thoroughly commingles and propels by means of the splay given by the 

 knives to the rollers, which are supplied through a chamber at the end of the 

 mill. These rollers force the clay through a die of hard wood or gun metal 

 of suitable dimensions to form the sides of the bricks. As the clay is thus 

 propelled in a solid and consistent body, it moves upon small rollers until it 

 comes within range of the cutting apparatus, which is a contrivance of six 

 wires attached to a frame sliding upon friction rollers. This frame is moved 

 suddenly backward and forward by the hand, separating the clay into five 



