MR. BABBAGE'S CALCULATING MACHINE. 293 



to prove extensively useful in various branches of 

 the mechanical arts. 



The drawings of this machinery, which form a 

 large part of the work, and on which all the con- 

 trivance has been bestowed, and all the alterations 

 made, cover upwards of 400 square feet of surf ace * 

 and are executed with extraordinary care and 

 precision. 



In so complex a piece of mechanism, in which 

 interrupted motions are propagated simultane- 

 ously along a great variety of trains of mechanism, 

 it might have been supposed that obstructions 

 would arise, or even incompatibilities occur, from 

 the impracticability of foreseeing all the possible 

 combinations of the parts ; but this doubt has 

 been entirely removed, by the constant employ- 

 ment of a system of mechanical notation invented 

 by Mr. Babbage, which places distinctly in view, 

 at every instant, the progress of motion through 

 all the parts of this or any other machine, and by 

 writing down in tables the times required for all 

 the movements, this method renders it easy to 

 avoid all risk of two opposite actions arriving at 

 the same instant at any part of the engine. 



In the printing part of the machine less pro- 

 gress has been made in the actual execution than 

 in the calculating part. The cause of this is the 

 greater difficulty of its contrivance, not for trans- 

 ferring the computations from the calculating 

 part to the copper or other plate destined to 

 receive it, but for giving to the plate itself that 

 number and variety of movements which the 

 forms adopted in printed tables may call for in 

 practice. 



The practical object of the calculating engine 



