(_a_) Hourly rate; (_b_) Monthly rate. The men who work by the month are apt to have to spend a good deal of non─productive time, on account of weather conditions, etc.; while the men who are on an hourly basis, as a general thing, do some profitable work whenever they are paid. It is feasible to figure a good deal more closely on the cost of work for those men who have practically no lost time to be taken care of, as _emergencies_ or _incidentals_. It will be noted, also, that the cost and the time of hourly and daily men can be figured and charted day by day; whereas it is impossible to know exactly what the charges will be for labor that is paid by the month, until the end of the month. In order to make report charts showing cost as completely as possible, it is a frequent practice to add a certain percentage to the cost of the known items, to cover the so─called _lost foremen's time_; and to make at the end of the month a correction of a greater or less size, in order to make the cost─keeping end tally with the bookkeeping end of the work. 2. GENERAL LABOR, ETC. This item will comprise the labor of the men who have something to do with more than a few parts of the work. A watchman's time is not spent in drilling, or on a steam shovel while it is running. Nevertheless a proportionate part of his salary should be divided among the different branches of the work. Sometimes this will be a very small item, sometimes a large item. For example, if a steam shovel is excavating 30,000 yards of material per month, the watchman's unit─charge to excavation may be very small; but if the shovel is tied up for nearly the whole month, the charge per unit for watchman's time may be alarmingly high. This is one reason why unit─cost and total cost should always go together. A blacksmith's time, part of which is spent in sharpening drills, need not be all chargeable to drilling, because he may spend a good deal of time in repairing the steam shovel or fixing hand tools, etc. 3. OVERHEAD LABOR. Clerks, bookkeepers, messengers, office force, and General Manager are ordinarily included among the items of _overhead charge_, as well as salaries of general officers. 4. OVERHEAD MATERIALS. In this classification, there are included stationery, office furniture, supplies, etc. When the office furniture is disposed of upon the completion of the work, its value should be credited upon this item. 5. OVERHEAD INCIDENTALS. These may include various items, such as telephone, office rent, telegraph messages, express charges on incidentals not directly connected with plant, etc. 6. PREPARATORY COSTS. These include the cost of getting ready to do the work, and, depending upon the nature of the job, may include any or all of the following items: