443 Contrivance for preventing Doors 



surface of these large grains, appearing^to me, no way dif- 

 ferent from the surface of the smallest siliceous grains, when 

 viewed by a m3gnifier proper for showing each under the 

 same apparent angle. I am, sir, your obedient servant, 



Commercial Inn. Sherfk-ki, JOHN FaRKY. 



June 6, I809j 



LXXIX. Contrivance for preventing Doors from Dragging 

 on Carpets. Bij Mr. John Tad*, 

 sir, 



X have taken the liberty of laying before the Society a 

 model of my invention to prevent doors from dragging on 

 carpets, and to keep out the current oF cold air, which en- 

 ters under such doors as are not close to the carpets under* 

 neath them. 



I can affix this machinery to the bottom of any door, so 

 that the door shall pass over the carpet with ease, and, when 

 shut, be air tight. Jt obviates the necessity of screw rising 

 hinges, and is less expensive than other inventions for the 

 same purpose. 



'The machinery is constructed of a slip of well seasoned 

 beech wood, equal in length to the width of the door; this 

 slip is one and a quarter inch wide, and half an inch thick, 

 and to be covered with gTeen cloth on the inside ; it is to 

 be hung to the bottom of the v door with three small brass 

 hinoes, and is drawn up by a concealed spring as the door 

 opens, and is forced down when the door shuts, by one end 

 of it, which is semicircular, pressing upon a concave semi- 

 circular piece of hard beech wood, fastened at the bottom of 

 the door case, and which holds it down close to the floor or 

 carpet, so as to exclude the air from entering under it. 

 Hoping this invention will meet with the approbation of the. 

 Society, I remain, with respect, 



Sir, your most humble servant, 



No. 4, Little Hermitage Street, Wapping, JOHN TAD. 



Nov. 24, 1807. 



To C. Taylor, M.D. Sec. 



* From Transactions of the Society for the Encouragement of Arts y Manufac- 

 tures, and Commerce, for 1808. Five guineas were voted to Mr. Tad for 



his communication* 



Reference 



