Stores record systems are quite commonly referred to as perpetual inventories, and, occasionally, such a system is pointed to as a failure for the reason that at the end of the year, or other fiscal period, the inventory, that is, the actual physical inventory of the stock, does not check with the records. The fact that systems of stores records have been regarded as inventories _in fact_, is responsible for most so─called failures. Regarded in its proper relation, a perpetual inventory is nothing more nor less than an accurate accounting of all goods that come into and go out of the establishment, these records to be checked by an actual physical inventory with such regularity and frequency that the accounts can safely be considered as exhibiting a correct inventory. In considering the question, how to take an inventory, we refer, therefore, to an actual physical inventory, that is, a count of every article in stock. When once this inventory is taken and properly recorded, it is entirely possible to install and maintain systems which will make it unnecessary to inventory all of the physical property at any one time. It has been the general custom in a large manufacturing establishment to shut down for a period of greater or less duration, running all the way from two or three days to as many weeks, for the purpose of taking an inventory. Since it has been considered necessary to shut down for this purpose, inventories have, as a rule, been taken but once a year. All this is unnecessary, for, with proper methods, it is possible to take even a complete inventory without perceptible interruption of the operation of the plant. The first step is to decide, at just what time the inventory is to be taken, and to have all foremen get their shops in readiness. This means a general cleaning up which will make it easy to locate and count, weigh, or measure the _materials_, _tools_, _supplies_, and _work in process_. Then, at a specified time the work of taking the inventory should be started simultaneously in every shop.