166 ELECTRICITY. 



Fig. 5. Plate III. Fig. 5, 6.— T. A bench standing on 

 four legs, about four feet from the ground. 



V, A circular cushion affixed to the ^bcnch, in the centre 

 of which cushion is an open space quite through the 

 bench, through which hole a leather strap U ii 

 brought up from below. This strap holds the work 

 and last firm upon the cushion in any position re- 

 quired, by means of the workman's foot placed upon 

 the treadle W. 



X, Shows the last upon the cushion, with the strap hold- 

 ing it firm. 



y, An implement used in closing boots, 



Z, A small flat leather cushion, useful in adjusting the 

 last and strap. 



Fig. 6. The shoe-last shown separate from the cushion. 

 The round cushion is formed of a circular piece of 

 wood, covered with leather or stuffed with wool 

 or hair to give it some elasticity. 



XVII. 



On the Propagation of Ekdridi^, By. Dr, 

 Oersted*. 



JL HE internal mechanism of the propagation of electric 

 city, has not, I believe been hitherto explained. It is 

 certainly very difficult to trace all the mystery of this pro, 

 cess, but it is certain that many interesting consequen- 

 ces may be deduced from the very nature of the subject, 

 aqd from the facts already known. 

 Phcnomenaof The first action of an electrified body upon one which 

 communica- is not electrified, is, as every body knows, to establish an 

 Ui^ of electri- ^^^^^^^^ polarity. Let A. Fig. 2 Plate IJI. describe an 

 electric body ; 1^, C, a cylindric conductor ; B will acquire 

 a negative electricity, whilst C becomes positive. This 

 is denominated the communication of electricity. It is 

 known also, that if the extremity C, of the conductor, be 

 deprived of its electricity, the conductor will retain onljr 

 the power of B, but on bringing A and B into contact, the 



f Ipscrtcd in the Journal de Physique, Vol. LXII. May i8o6. 



contrary 



