The isolated group of labourers to whom any particular detail
 function is assigned, is made up of homogeneous elements, and is one of
 the constituent parts of the total mechanism. In many manufactures, however,
 the group itself is an organised body of labour, the total mechanism being
 a repetition or multiplication of these elementary organisms. Take, for
 instance, the manufacture of glass bottles. It may be resolved into three
 essentially different stages. First, the preliminary stage, consisting
 of the preparation of the components of the glass, mixing the sand and
 lime, &c., and melting them into a fluid mass of glass. [15] Various detail labourers are employed in this first stage, as also in the final one of removing the bottles from the drying furnace, sorting and
 packing them, &c. In the middle, between these two stages, comes the
 glass melting proper, the manipulation of the fluid mass. At each mouth
 of the furnace, there works a group, called “the hole,” consisting of one
 bottlemaker or finisher, one blower, one gatherer, one putter-up or whetter-off,
 and one taker-in. These five detail workers are so many special organs
 of a single working organism that acts only as a whole, and therefore can
 operate only by the direct co-operation of the whole five. The whole body
 is paralysed if but one of its members be wanting. But a glass furnace
 has several openings (in England from 4 to 6), each of which contains an
 earthenware melting-pot full of molten glass, and employs a similar five-membered
 group of workers. The organisation of each group is based on division of
 labour, but the bond between the different groups is simple co-operation,
 which, by using in common one of the means of production, the furnace,
 causes it to be more economically consumed. Such a furnace, with its 4-6
 groups, constitutes a glass house; and a glass manufactory comprises a
 number of such glass houses, together with the apparatus and workmen requisite
 for the preparatory and final stages.