ERRATA, &c. 



Page 155 line 3 from bottom, omit = at the end. 



158 Tredgold has made use of the moment of the pressure of the steam instead of the actual 

 pressure on the parts. 



The force at the distance x from E is/y d x, which multiplied into 2 it (r + x), the space 

 described, gives Ifnydx (r + x) ; and the integral is fir a y (2 r + a), the power expended 

 on each revolution. It is hence plain that no power is lost, the factor n a y (2 r + a) being 



the volume of steam employed at the pressure/. 

 1641 



jgg | Arts. 333, 342, foot-notes and other parts depending on the same, are incorrect in principle. 



The greatest effect is generally produced with the least velocity ; the effect being the 

 effective force multiplied into the space through which it is exerted. 

 ,, 263 line 11 from bottom, for second read minute. 

 ,, 393 lines 4 and 5 from bottom, transpose LXII. and LXIII. 



APPENDIX. 



Page 128 at the bottom on the left, for r a 3 sin. ft read 2 r a 3 sin. /3. 



Plate xi. The adjustment of the parallel motion is wrong ; the same radius bar will not do for both 

 ends of the beam. In the plate, the motions for the cylinders and air pump are correct; but 

 the pump rods on the left cannot move in straight lines with such an arrangement. 



We are indebted to Professor Willis, of Cambridge, for a notice of this error. 



