JHYLUM, JELUM, BEHUT, or VIDUSTA, the ancient Hydaspes, a large river of Hindustan, which has its rise in the south-east corner of the valley of Cashmere, in the great Himalaya ridge of mountains. It is there called Vidusta, and passes through two lakes east and west of the town of Cashmere. It is joined, ten miles below the town, by the Little Sinde, and receives many small rivulets in its course through the valley and hills, which it enters at Baramoola; and, four miles below Moozufferabad, it receives the Kishungunga from the north; its course thus far being nearly west. From this it takes a great curve to the south, and near Jelum it is little known, the country being so excessively mountainous that few travellers ever pass that way. In its course through the hills this river is very rapid, and from 100 to 200 yards broad. It is not fordable at any season, though in many places nearly so, as men and horses cross with ease, having only fifteen or twenty yards to swim. After a course of 450 miles, it joins the Chunab at Trimmo Ghat, eighteen miles below Jhung, and ninety-five above Moultan, in which it loses its name. These joint streams, called the Chunab or Chunha, receive the Ravee forty-eight miles lower down, near Fazilshah and Ahmedpoor, from the eastward, and pass four miles north of Moultan, retaining the name of Chunab to within seven miles of Ooch, where they are joined at Sheeneebukree by the Gharra, or joint streams of the Beyah and Sutledj, 112 miles below Moultan, and sixty miles below Buhawulpore. From this point to Mittenda Khot, where they fall into the Indus, about seventy-six miles, these five streams take the name of the Punjab. The Indus, and the Punjab, or the five rivers, run parallel to each other for this distance, which is about ten and a half miles. The whole of this space is one complete sheet of water during the rains and hot season, and appears as one river. The greatest breadth between the Jhylum and the Indus appears to be 114 miles from Attock to Jellalapore Ghat. The whole course of the Jhylum, including its windings, may be estimated to exceed 400 miles.
Jib, the foremost sail of a ship, being a large stay-sail, extended from the outer end of the boltsprit, and prolonged by the jib-boom, towards the fore-top mast head. See SAIL.
Jib-Boom, a boom run out from the extremity of the boltsprit, parallel to its length, and serving to extend the bottom of the jib, and the stay of the foretop-gallant mast. This boom, which is nothing more than a continuation of the boltsprit forward, to which it may be considered as a top-mast, is usually attached to the boltsprit by means of two large boom-irons, or by one boom-iron, and a cap on the outer end of the boltsprit; or, finally, by the cap without and a strong lashing within, instead of a boom-iron, which is generally the method of securing it in small merchant ships.