Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

Smeaton's John Smeaton in 1788 designed a diving bell for use in repairing the foundations First J , _ Bel1- of Hexham Bridge, but instead of weighted barrels, he introduced here for the first time Fig. 94. a force pump for supplying the necessary air. This bell was never intended to be wholly submerged, and, as will be seen from the illustration, the pump used for supply- ing air was fixed on the roof of the bell. To Smeaton, too, we are indebted lor the first diving bell plant in the form with which we are familiar to-day, that celebrated engineer having designed a square bell of iron, for use on the Ramsgate Harbour Works in 1790. The following is Smeaton’s own description, taken from his 11 Historical Report on Ramsgate Harbour,” written in 1791 :— “I had scarcely returned from this visitation before a requisition came to desire the SS expedient I had mentioned might be got ready, and which was done with such expedition BM- that I set forward for Ramsgate the 6th July m order to put it muse; and the 12th 1 le Ramsgate after a full trial of the Diving Chest, and with the certainty of success. “ Instead of the usual form of a Bell, or of a conical tub of wood sunk by weights (externally applied), this, for convenience, was a square chest of cast iron, whic 1 eing 50 cwt., was heavy enough to sink itself; and, being 4I feet in height, 4a feet in length, and 2 feet wide, afforded room for two men at a time to work under it. But it was peculiar to this machine that the men therein were supplied with a constant influx of fresh air, without any attention of theirs ; that necessary article being amply supplied by a forcing Air 1 ump, in a boat, upon the water’s surface. “With this machine, which enabled the workmen to stay under water any length of time at pleasure, when the wind was moderate, that the boats could attend, in the course of that and part of the following month, the foundation was cleared; and the tools tor levelling of the ground, the same that were originally invented and applied by t le a e in- genious Mr. Etheridge, were now put in use, under the management of Mr. Cull, the Master Mason, who had formerly been employed in that part of the business, it being the Chairman s wish, as best for the work, that everything should go on in the same method as originally practised. It was computed that about 160 tons of stones had been got up in clearing the foundation, and that about 100 tons thereof had been raised by the Diving Machine, many of above a ton each ; but the want of the Machine would doubtless have been the loss of t c season.”