412 ANNUAL KECOKD OF SCIENCE AND INDUSTRY. 



is attached to a plate, which has a slit and set screw, so that 

 it can be moved forward or backward slightly, and thus be 

 adjusted to any inaccuracies in hanging the door. The up- 

 per pivot is let into the top of the door and rests upon one 

 end of a lever, also let into the top of the door, and is forced 

 up into the socket by a screw acting on the other end of the 

 lever, nearer the front of the door, thus rendering it easy to 

 hang or remove. 5 C, XL VI., 366. 



MYSTEEIOUS CLOCKS. 



Robert, of Paris, has succeeded in carrying out practically 

 an old suggestion for the construction of clocks apparently 

 without works, by employing aluminium for the light parts, 

 and platinum for a movable weight. The clocks, as made 

 by him, seem to consist simply of a glass face, supplied with 

 two hands, to which counterpoised weights are attached. 

 These latter, however, contain diminutive works, which vary 

 the position of a piece of platinum in such a way that its 

 weisht, in connection with that of the hands themselves, 

 causes them to turn. 6 (7, June 3, 1875, 216. 



PEEVENTIOX OF THE CRACKING OFF OF GLUE. 



The cracking of glue, which frequently occurs when glued 

 objects become very dry or are subjected to the heat of a 

 stove, it is said, may be prevented by the addition of chlo- 

 ride of calcium to the glue, which prevents its drying so com- 

 pletely as to become brittle. Glue thus treated will adhere 

 to glass, metals, etc., and can be employed for affixing labels 

 to bottles. 5 (7, XXXVIIL, 304. 



NEW LIFE-SAVING DEVICE. 



The Paris Maritime Exhibition afforded the opportunity 

 for the experimental demonstration of the great value of the 

 " Gay Safety Mattress," an indorsement in which all accounts 

 agree. The device, which is both a mattress and, in case of 

 necessity, a life-preserver, is formed of two rows of blocks 

 made of cork - cuttings, lightly compressed by machinery 

 within a water-proof case, and the whole covered with can- 

 vas. It forms ordinarily a mattress, which is intended to be 

 placed in every cot or berth, and makes a bed which is said to 

 be very elastic and easy to lie upon. Its weight is about six 



