Because of the constantly growing demand for wool, many were induced to raise sheep and to trade in the raw wool. Records show that Belshazzar, son of the king and heir to the Babylonian throne, was a wool-merchant on a large scale, his commercial interests being, of course, managed by others. The price of wool varied greatly, being sometimes high, sometimes low. It cost little in addition to the wages of the shepherd to pasture flocks west of the river during the greater part of the year, for pasturage there was free to all. For some months, to be sure, sheep had to be sheltered and fed inside enclosures, within or near the city. This was the costly part of sheep-raising. When the flocks were driven into town, toll per head was exacted at the city gate. Lists of the various tolls collected and turned into the general treasury show them altogether to have been considerable; not only were they collected of all who passed through the gates but a bridge toll was paid by whoever passed over the bridge connecting Babylon and Borsippa, across the river; all ships and sailing crafts, moreover, paid a toll to pass under the bridge. Enumerations of the trades of Babylonia have been found; these mention the trades of carpenter, smith, metal-worker, weaver, leather-worker, dyer, potter, brick-maker and vintner. The carpenter not only raised the beams and scaffolding of houses, but as well made whatever articles of furniture the times afforded. The brick-maker made tablets for inscriptions as well as bricks for building purposes. The brickyards were always on low land, near the river, where reeds, so useful in brick-making, were abundant. Building bricks were made in different sizes--some nearly a foot square by 2-1/2 inches thick; others about 15 by 15 and three inches in thickness. Chopped reeds were frequently mixed in the bricks themselves, and since the demand for them was constant, they were cultivated and grown in large areas. In a secluded corner of the brickyard, the fine tablets for literary purposes were produced; and here too, dishes and vases of pottery were molded and baked. Thus we see that great activity and divers interests attached to these yards given over to the manufacture of clay articles. The leather worker found material in abundance, owing to the extensive cattle raising. Harnesses, saddles, and shoes, beautifully decorated, were chief among leather commodities. The smith excelled in fashioning articles from gold, silver, copper and bronze. Ordinarily the metal was melted and run into molds of clay or stone. The customer usually furnished the ore and paid for the work upon it. Metal workers were held accountable for the excellence of their work, as is shown by guaranties found, whereby they promised to pay heavy fines if during a given term of years, their work should be found imperfect.