The manner in which bees carry on their work is as follows. In the day time a guard is stationed at the entrance of the hive, like the sentries in a camp. At night they take their rest until the morning, when one of them awakes the rest with a humming noise, repeated twice or thrice, just as though it were sounding a trumpet. They then take their flight in a body, if the day is likely to turn out fine; for they have the gift of foreknowing wind and rain, and in such case will keep close within their dwellings. On the other hand, when the weather is fine—and this, too, they have the power of foreknowing—the swarm issues forth, and at once applies itself to its work, some loading their legs from the flowers, while others fill their mouths with water, and charge the downy surface of their bodies with drops of liquid. Those among them that are young[26] go forth to their labours, and collect the materials already mentioned, while those that are more aged stay within the hives and work. The bees whose business it is to carry the flowers, with their fore feet load their thighs, which Nature has made rough for the purpose, and with their trunks load their fore feet: bending beneath their load, they then return to the hive, where there are three or four bees ready to receive them, and aid in discharging their burdens. For, within the hive as well, they have their allotted duties to perform: some are engaged in building, others in smoothing, the combs, while others again are occupied in passing on the materials, and others in preparing food[27] from the provision which has been brought; that there may be no unequal division, either in their labour, their food, or the distribution of their time, they do not even feed separately. Commencing at the vaulted roof of the hive, they begin the construction of their cells, and, just as we do in the manufacture of a web, they construct their cells from top to bottom, taking care to leave two passages around each compartment, for the entrance of some and the exit of others. The combs, which are fastened to the hive in the upper part, and in a slight degree also at the sides, adhere to each other, and are thus suspended altogether. They do not touch the floor of the hive, and are either angular or round, according to its shape; sometimes, in fact, they are both angular and round at once, when two swarms are living in unison, but have dissimilar modes of operation. They prop up the combs that are likely to fall, by means of arched pillars, at intervals springing from the floor, so as to leave them a passage for the purpose of effecting repairs. The first three ranks of their cells are generally left empty when constructed, that there may be nothing exposed to view which may invite theft; and it is the last ones, more especially, that are filled with honey: hence it is that the combs are always taken out at the back of the hive.