Mechanical time recorders, or time clocks, are of two general types, making two classes of records. One type records the time of one employe on a single card or sheet; the other makes a record of the time of several employes on the same sheet. For recording the total time of employes, both types are used, and certain advantages are claimed for each. [Illustration: Fig. 5. Rochester Time Recorder, Manufactured by International Time Recording Co.] The records of the first type, most generally used, have a card for each employe on which a record is made of his time for an entire week or pay period. In operation, this system is very simple. At each side of the clock is a card rack, as shown in Fig. 5. One of these is an "out" rack, the other an "in" rack. At the beginning of each week or pay period, cards are placed in the numbered pockets of the out rack, which is nearest the entrance──one card for each man. These cards bear the numbers or names of the men, or both if desired. When the employe enters, he takes his card from the out rack, places it in the slot of the clock, makes an exact record of the time of arrival by moving a lever, and places the card in the proper numbered pocket in the in rack. When he leaves, the operation is repeated, this time the card being deposited in the out rack. In the meantime the recording device in the clock has been shifted so that it records the leaving time in the proper column on the card. The form of record made by one of the best known clocks of this type is shown in Fig. 6. It will be noted that the recording device prints the letter representing the day of the week in front of each record──out or in. Another feature is the dash under the afternoon registrations; a glance shows whether the registration was made at, for instance, 6 o'clock in the morning or afternoon. [Illustration: Fig. 6. Weekly Time Pay Card Used in the Rochester Recorder] This form requires an exceptionally small number of entries to figure the time for the week. In the outside column, at the right, is entered the time lost or the overtime for each day. At the end of the week, the net total of this column is added to or subtracted from the total hours representing a full week, which gives the total number of hours actually worked. Clocks of the second type record the time of several employes on one sheet, the record being made for one day, or for any number of days up to a week. Like the card machine, the record shows the in and out time, both forenoon and afternoon. A recorder of this type is illustrated by Fig. 7. To register the time of arrival or departure, the employe places a key, bearing his number, in the clock, and gives it one turn. A bell rings, indicating that the hour and minute of the day have been printed on the record inside the register. [Illustration: Fig. 7. The Bundy Time Recorder, Manufactured by International Time Recorder Co.]