368
HISTOttY OF ENGINEERING.
Book I.
abound with felspar, which is of a brownish colour, and contain a number of irregularshaped white specks; they dip towards the north-west, at the rate of about one perpendicular to two horizontal.
Un tne days ot tun moon it is nigh water atthe Eddystone at a quarter past five o’clock ;the tide of flood sets easterly, or up Channel,and the ebb tide sets westerly ; spring tidesrise from 16 to 18 feet, and neap tides from10 to 11 feet: at these rocks, and upon theopposite shores, it is high water about hourssooner than in the middle of the Channel.
The first lighthouse was commenced in theyear 1696 under the general powers lodged inthe Masters, Wardens, and Assistants of theTrinity House, who were empowered in thereign of Elizabeth to erect and set up beacons,marks, and signs for the sea, needful for avoid-ing the dangers, and to renew, continue, andmaintain the same.
Mr. Henry Winstanley , of Littlebury, inthe county of Essex , was the engineer boldenough to undertake this building, which oc-cupied three years in constructing; he com-menced by making twelve holes in the rock,and introducing as many irons 3£ inches indiameter, around which he carried up a massof masonry 14 feet in diameter, 12 feet highupon the upper side, and 17 feet on the lower ;on this was constructed the upper stories,which were probably of timber.
The base was afterwards increased, so thatits diameter was 24 feet ; above this, thestructure had a polygonal form of twelvesides, and the upper or look-out room hadeight ; the whole underwent a thoroughchange, or reconstruction, and the lighthouse,as completed in 1699, bore no resemblance tothe first design.
On November 26. 1703, a violent stormcarried away the lighthouse; and Mr. Win-stanley , the workmen employed in its repair,and the light-keepers, all perished.
Mr. John Rudyerd, a silk-mercer uponLudgate Hill, was in the year 1706 em-ployed to reconstruct it; and whatever herequired as a mechanist was ably supplied bytwo shipwrights from the king’s yard atWoolwich. A circle was the form be selectedfor the plan of the new building, and aftermaking a number of holes in the rock bymeans of jumpers, he inserted the ironbranches, to hold his work firmly to the foun-dations prepared for it. The holes were 2 \inches in diameter, and the extremities of thetwo which formed the breadth for the branchat the surface of the rock were about 7^ inches,and these holes were bored slanting, so that atthe bottom they were full 8^ inches apart.Between every two holes was bored a third,and afterwards the rock between them wasbroken away by square-faced pummels, whena hole of a dovetailed shape was obtained
inches wide, 7^ inches broad at top, and''8.^ inches at bottom, and in depth 15 or 16inches. These holes -were not exactly alikein dimension, and it became necessary toforge an iron expressly to fit each.
Fig. 370.