Gear's illustrated catalogue of wood and iron working machinery (1872)
A.S. Gear, Gear, A. S · Boston : Printed at A.S. Gear's printing office, 62 Sudbury Street · leaf 76
f tf tftftt m ;^pifcil ^prii\^ ;^kwrq^ ^k6l\ii\e. … The above cut represents the machine set up in perfect order. A A are two spiral springs made from Jessups bestimported English steel. Each spring contains ten coils of i or J round steel rod, one being a right hand, the other aleft hand coil. One end of each of these springs is firmly fastened to…
