It is especially important that the makers and also the sellers of pumps and pumping machinery should be informed regarding the proper type, size, pattern and _proportion of parts_ for any peculiar service, as well as to the plan of their connections and the kind of material to be used in their construction. This information regarding the conditions of the service under which the pump is to be worked is quite pertinent to the foregoing pages regarding the parts of pumps. The following questions are extracted from the catalogue of an extensive manufacturer. _First_—To what service is it to be applied? _Second_—The quality of the liquid to be pumped, whether salt, fresh, acid, clear or gritty, and whether cold or hot? _Third_—To what _height_ is the water to be lifted by _suction_, and what are the length and diameter of the suction and discharge pipes? _Fourth_—Of what material is the suction pipe, and what is its general arrangement as regards other pipes leading into it, etc.? _Fifth_—Will the supply be taken from a driven well? If not, from what source? _Sixth_—To what height, or against what pressure, is the water to be pumped? _Seventh_—What is the greatest quantity of water to be delivered per hour? _Eighth_—What boiler pressure of steam is carried? _Ninth_—Will the pump exhaust into the atmosphere, into a condenser, or against a back pressure? If the latter, how much? BELTED PUMPS. [Illustration: FIG. 205.] Fig. 205 represents an approved form of steam boiler feed pump, single acting. It has a crank shaft and a tight and loose pulley. It may be driven direct from any line shaft, a countershaft being unnecessary. This is a compact form of a boiler feed pump; formerly the pump crank shaft was attached to floor beams or timbers above and connected by a long pitman to the pump which stood upon the floor; the objections to the older system of apparatus were found to be the vibration of the long pitman and the springing of the floors. To obviate these two difficulties the pump and countershaft were attached to a post bringing them nearer together but finally resulting in the design of pump here shown. The broad base insures great stability in the operation of the pump especially when fixed to a rigid floor or timber foundation. In the Table below are given some details furnished by the makers relating to six sizes of this style of pump, to which may be added that _the speed_ ordinarily used varies from 100 revolutions per minute for the small sizes, to 20 revolutions for the larger sizes. TABLE.