The key-driven machine, which was the first produced of these two types of modern machines, does not print, and is used for all forms of calculation, but is generally behind the scenes in the accounting rooms of all lines of business, and for that reason is not so well known as the key-set crank-operated or motor-driven machine, which is designed to print and is always in full view in the bank where it is used to print your statement of account from the vouchers you have issued. When we stop to analyze the qualities of these two types of machines, we find that each has its place and that neither may truly serve to displace the other. The organization of each is designed with reference to the special work it was intended to do. The calculating machine, having only to perform the work of revolving the numeral wheels in calculating addition, subtraction, multiplication and division in its many forms and combinations, may be key-driven (on account of the slight mechanical resistance met with in action), and thus, as a one-motion machine, requiring only the depression of the keys, may also be much more rapid of manipulation than the two-motion recording-adding machine which, after depressing the keys for each item, requires the secondary operation of pulling a crank forward or operating a push bar that connects the motor. The recording-adding machine being designed to print the items and answers of addition, requires power for the printing which cannot be supplied by key depression. Thus an extra means for supplying that power must be provided in the form of a crank lever, or in the latest machines by a motor. The keys in such machines serve only as digital control to gauge the setting of mechanism which prints the items and adds them together. The secondary motion operates the mechanism to print and add and finally to clear the machine for the setting up of the next item. The recording of added columns of figures requires that the answer must always be printed. This demands special operation of devices provided for that purpose, which also adds to the time spent in the operation of such machines as compared with the key-driven calculator. [Sidenote: _Recording, the primary feature of adding machines that print_] To state which of these two types of machines is the more useful would cause a shower of comment, and has nothing to do with the object of this article. Suffice it to say that where a printed record of items added together with their answer is required for filing purposes, or to bring together loose items like those in your bank statement, the recording-adding machine serves; but when rapid calculation in addition, multiplication, subtraction or division, or when combinations of these forms of calculation are required, the key-driven calculator is the practical machine for such work.