The idea of a tide-basin with boom-gates facing the breach of Atlantic waves is somewhat novel and was not very hastily entertained by me at first; but the most complete success has attended the plan. During my occasional visits to the works in the course of the summer 1843, our attention had been often occupied with considering the probability of the sand shutting up the basin; and as a single tide during heavy winds from the N.W., made great changes on the appearance of the beach, we feared that the vessel might often be imprisoned within the boomgates by a bank of sand heaped against them by the sea. To such an extent did the accumulation go before the harbour was fully opened, that on many occasions there was not water for a rowboat to pass between the boom-heads even at the highest spring-tides. The only remedy for such an evil, was obviously to attempt some mode of artificial scouring; and for that purpose, it was proposed to divert several small streams which run from Ben Hynish and the neighbouring hills through the grounds at Hynish, into one feeder, and pen them up in a pond, so as to afford the means of scouring the entrance to the basin from the incumbrance of the loose sand which might choke it. Those streams were repeatedly gauged during the summer and were found to deliver from 13 to 50 cubic feet of water per minute, according to the state of the weather,--a supply which seemed ample for the purpose in view. The sand at Hynish is of a light nature and is easily acted on by currents of very feeble power. It consists of comminuted shells and requires about 25¹⁄₂ cubic feet to make a ton, instead of 24 feet, which is the common allowance for silicious sand. The leave of the Duke of Argyll and also of the Farmer at Hynish, having been obtained, various cuts were made and the stream was diverted into a pond capable of containing about 175,000 cubic feet and provided with a waste-weir and with sluices for opening the communication between the pond and the scouring tunnel, from which the water flows in a stream of about 9 square feet of area, at the rate of about 260 feet per minute for a period of 1¹⁄₄ hour. The operation of scouring is performed at low water and is generally found quite sufficient for the purpose of clearing a passage down to the bare rock in a single tide. Nothing can be more satisfactory than to witness the effect of that process in opening the entrance to a basin apparently inaccessible; and but for such an arrangement, the dock must have remained permanently choked with sand and sea-weed. The position of the various works is marked in Plate X., which shews the ground at Hynish.