iv 



which Mr. Appold devised the most deUcate apparatus to meet any want. 

 By the use of this instrument the flow of a small stream of water over a 

 warm stove was regulated, and by this means one uniform hygrometric 

 state of the atmosphere was ensured throughout the building. The bel- 

 lows he applied to prevent the jar of slamming doors is an ingenious and 

 effective apparatus ; and the Appold Pneumatic Valve, for preventing 

 down draughts with very feeble currents, acts perfectly. 



Mr. Appold' s mechanical contrivances were innumerable, and many of 

 them distinguished by their extreme originality. Perhaps the most re- 

 markable is the scrubber, devised to remove deposits from the inside of the 

 water-pipes of a town. This has been used with perfect success at Torquay, 

 but it is to be regretted that he never himself knew that his design answered 

 its expectations. It was a question whether the main pipes of Torquay 

 would not have to be removed, but the action of the scrubber was so per- 

 fect, that the deposit was entirely disintegrated and carried av^'ay with the 

 flow of water. In his factory many remarkable devices existed. Pumps 

 v/ere curiously arranged to throw on and off as they were required ; and air 

 was supplied to the steam-engine fire by self-regulating apparatus. 



Besides his more important contrivances he made some for mere amuse- 

 ment; and every part of his house bore testimony to the fertility of his ima- 

 gination and power of invention. Doors were made to open on approach, 

 and to shut after the person had passed through ; others locked themselves 

 afterwards. He had contrivances also by which all the shutters of a room 

 closed by the touch of a spring, and thus, when associated with the regu- 

 lator of a gas-lamp, caused a change from daylight to gaslight, to the no 

 small amusement of his visitors. All his numerous contrivances acted 

 perfectly, even to the unimportant matter of his self-acting stable-gates, 

 which when once adjusted, were so exact in their mechanism that they 

 remained in use for years without requiring attention. 



Shortly before his death he was constructing an apparatus for measuring 

 accurately the pitching and rolling of vessels at sea. 



Mr. Appold showed a knowledge of the laws of heat by constructing a 

 thermometer of extreme delicacy for a range of a few degrees. It consisted 

 of a thin plate of zinc and steel rivetted together, and suspended on a knife- 

 edge, so that its bar was unequally balanced. This form of thermometer 

 is difficult to manufacture, otherwise it would doubtless be in general use 

 for sitting-rooms and greenhouses, as it indicates distinctly a variation of a 

 tenth of a degree, which can be read across the room. He also constructed 

 a motor thermometer to regulate the supply of gas to a stove according to 

 the temperature of an apartment at a considerable distance, and this acted 

 in the most efficient manner. 



One very curious application of physiological experiment Mr. Appold has 

 left us in connexion with the Daguerreotype. In the early days of stereo- 

 scopic photography he conceived the idea that from the superposition in 



