Page:Graphic methods for presenting facts (1914).djvu/343

 After any group of cards has been run through the machine the totals can be read off from the counting dials and written down by the operator. Then the machine is ready for some other set of cards. Machines are built with different numbers of counting heads to suit the complexity of the data in any kind of business. By having several counting heads on the same machine, different sets of information may be taken from the cards simultaneously, thus frequently permitting one run of the cards through a tabulating machine to give all the data which may be required.

Courtesy of the Tabulating Machine Company

Fig. 230. Hollerith Tabulating Machine for Totalling the Data Contained on Punched Cards

The machine illustrated has four counters, permitting the simultaneous taking off of the data contained under four different headings on the punched card. The sorted cards are placed at the left of the tabulating machine and run through at the rate of about 3,000 per hour. Totals are read from the dials shown at the right

The punched-card machines are proving to be of very great usefulness in commercial work. Fig. 231 gives a view of a completely equipped office for the use of the punched-card system by an electric lighting company. The data are transferred from the original records to the cards by very simple punching machines with keys somewhat similar to typewriter keys. The punching is usually done by girls. A little training and practice gives high speed. Once punched, the cards are always available and may be filed for record purposes. It is frequently a great convenience to be able to run through the machines cards for several years back so that comparative statistics may be made. The preservation of the cards makes it unnecessary to dig out the original records. The uniform size of the cards makes it possible to preserve large quantities of them with comparatively little labor.

In punching the cards there are certain holes relating to departments, dates, etc., which are repeated time after time for large numbers