•' At 1 I, in in, two of the ribs are supposed taken out, to show their bearings upon the rings ; they were open centres, that it might be seen underneath when the joints were Ur.
"Figure 7, of Plate IV., shows how the sixteen radii of stones would apply to the sixteen ribs. In this plan, Figore 4„t shows the wenhole, and n n the cross timbers for supporting; the four middle posts, whose places are marked out by dotted little squares.
" Figure 5. An elevation, and Figure 6, the relative plan if a dial stone, taken professedly from the general figure of the Eddystone lighthouse ; being the design of the late James, 1)tike of Queensberry, and by him erected at Ames bury, Wilts, with a dial upon it, by Mr. Itam.sden. The drawing, of which this is a copy, was given me by the Duke ; and is placed here as an instance, that the Eddystone column may be applied to some uses oh' architecture.
" Figure 7. One of the silver medals given to the seamen as a token of the service.
" Figure 8. The tool wherewith the stones were got up from the bottom of the gut.
" A. One of the stones with two trenail holes.
" Suppose this stone lying flat in the bottom of the gut, the side A uppermost. The tool has a pole or staff. b h, about twelve feet long. sufficient to reach the bottom. This single prong, c, is forged to a very single taper, such as to be thrust eight or nine inches into a trenail hole. (all of them being bored to a gauge) it can be driven bv the pole, till fast ; observing that the arm e corresponds to the centre of gravity of the stone. The water is generally so clear as to see to the bottom ; and, in case of any ruffle by the wind, can be in a great measure freed from agitation, by looking through a speaking- trumpet, whose mouth is put down eight or ten inches into the water. The rope d e / being then set upon by the main tackle, instead of its drawing out, the length of the arm y causes the prong to jamb the faster in the hole ; and the staff quitted by the hand, with a cord to hinder its flying too 'fitr, the whole assumes the position of the figure ; and, when brought above water, is lowered into a yawl.
" Figure 9. A section of one of the mortar buckets, and in it the beater.
"Figure 10. One of the internal flices'of the lantern's glass frames, and therein the cross bars of iron. as they were actually fixed. Besides the flat at each end of eavh bar, distinguished by a darker shade, and through which the screws passed ; each end was also cranked about an inch, so as to set the transverse part of the bars clear of the copper sash-frame ; and they were cleared of each other at their intersection, by one of them being made straight, the other curved in that part. All the panes being taller than the
candles, the chandelier rings are so hung, that when the candles are at rest, dispensing their light, that of one chan delier passes through the range of panes n, and that of the other through the range B j and when the candles are snuffed, one of the rings of lights being seen through the range c, the other mounts to n, and vice versa.
" Figure 11. The chain of triangles from the Eddystone to the flag-staff of the garrison of Plymouth, for ascertaining their distance trigonometrically.
" Figure 12. An enlargement of the work within the headlands of the Sound.
"The whole country about Plymouth Sound being very uneven, 1 could not readily obtain a base better, than by very carefully measuring the two lines n a, n w, taking the intercepted angle w n o ; whence the right line w o was obtained, making a base of 1871 feet, and which I cannot suppose to err more than half a foot. Again, the nearest place from whence the two beacons, w, a, could be commo diously seen for the purpose, was the point s; and all the three angles of the triangle w s G, being likewise carefully taken, I conclude the angle w s c = 10° 23', taken true to a minute ; that is, to d part of the whole angle. The line s w could therefore be determined within part ; which being considered as a new base of larger extent, may be esteemed true within-thth part of the whole. From this, and the angles taken as marked upon the scheme, the lines w w m, and iv E, were successively determined ; and finally F E, the distance of the flag-staff from the Eddystone, carte out very near, but somewhat less, than fourteen miles. But the interior harbour of Plymouth, called Sutton Pool, being about three furlongs farther from the Eddystone, than the Ilag.staff, the whole distance may be esteemed fourteen miles and a quarter from Plymouth harbour." Thus was completed the. Eddystone Lighthouse, which must ever be a masterpiece of its kind. The merit of utility is not its only characteristic; but in beauty, as Nvull as in strength and originality, it deserves the highest amdiration. And when we remember the extraordinary difficulties by which a work like this must have been surro?mded, we must own, that had its contractor left no other memento of his genius, the Eddystone alone would be sullic'ent to hninortalize the nanie of Smeaton.
EDt;E, the intersection of the two planes or surfaces of a solid, which is consequently either straight or curved accord ing to the direction of the suribees. See A RRIS.