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Show OIL ON WATER. NoTE XXIX. of the greate!l: tenuity. But if a fecond drop of oil be put upon the former, ~t does not fp read itfelf, but remains in the form of a drop, as the other already occup1 erl the whole furface of the bafon, ::md there is friCtion in oil paiTtng over oil, though none in oil paiTtng over water. Hence when oil is diffufed on the furface of water gentle breezes have no influence in raifing waves upon it; for a fmall quantity of oil will cover a very great furface of water, (I fuppofe a fpoonful will diffufe itfdf over fame acres) and the wind blowing upon th is carries it gradually forwards : and there being no friCt:ion between the two fmfaces the water is not affected. On which account oil has no effect in flilling the agitation of the water after the wind ceafes, as was found by the experiments of Dr. Franklin. This circum!l:ance, lately brought into noti ce by Dr. Franklin, had been mentioned by Pliny, and is faid to be in ufe by the divers for pearls, who in windy weather take down with them a little oil in their mouths, which they occafionally give out when the inequality of the fupernatant waves prevents them from feeing fufficiently diflinC\.ly for their purpofe. • The wonderful tenuity with which oil can be fpread upon water is evin ced by a fevv drops projected from a. bridge, where the eye is properly placed over it, pafling through all the prifmatic colours as it di ffufes itfelf. And al fo from another c urious experiment of Dr. Franklin's: he cut a piece of cork to about the fi ze of a letter-wafer, leaving a point !l:anding off like a tangent at one edge of the circle. This piece of cor k was then dipped in oil and thrown into a large pond of water, and as the oil flowed off at the point, the cork-wafer continued to revolve in a contrary direCtion for feveral minutes. The oil flowing off all that time at the poi nted tangent in colomcd fl:reams. In a fmall pond of water thi s experiment docs not fo well fu ccccd, as the circulation of the cork !tops as foon as the water becomes covered with the pelli cle of oil. See Additional N ote, No. XIII. and Note on Fucus, Vol. II. The eafe with which oi l and water flidc over e::1ch other is ag reeably fccn if a phi al be about half filled with equal parts of oil and water, and made to ofcill ate f11fp cndcd by a fhin g, the upper furface of th e oil and the lower one of the water will always k eep fmooth; but the agitation of the fur faces where the oi I am! water meet, is c uriam ; for their fp cci fic gravities being not very different, and their fri C\.iun on each other nothing , the highe!l: fide of the water, as tha phial clcfcends in its ofc ill ation, having acquired a greater momentum than the lowcfl fide (from its having clefcendcd fu rther) would rife the highe!l: on the a fcending file of the ofcillation, and thence pufhcs the then uppermofl part of the water amongfl: the oil. [ 77 ] NOTE XXX.-SHIP-WORM. M eet jtll 'Tcredo~ as be mines the keel Wilb beaked head, and break his lips of flee!. CANTO III. I. 9I. T· HE T eredo, or fhip-worm ' has t\vo ca· lc arcousj.a ws h ·li h · <~nd angular behind. The fhell · . . ' emt P enca1, flat before, IS taper, wmdmg penetrati fh. d li wood, and was brought from India i t E L .' . ng tps an ubmarine . n o urope. mnet Syflem N 6 Taneres, or fea-worms, attack and crod fh. . h li · at. P· I2 7· The c 1ps Wtt uch fury I · ii 1 :~soften greatly to endanger th em It. r .cl I . ' anc Ill uc 1 numbers, • IS !at t lat our ve[e!s have not k h. enemy above fi fty vears, that they were brougllt f h r nown t IS new ' rom t e 1ea about the A t"ll partS of the OCean, where they have increafed d. . fl n I CS tO our · h · . pro tgwu Y · They bore the· ffi 111 t c dtrcctwn of the fibres of the wood h. I .. h . . lr pa age . ' w IC 1 IS t e~r nounfhment, and cannot r turn or pafs obl1quely, and thence when they come to k . h e-f a not m t e wood or wh o them meet together wi th their ftony mouths th " tL fi ' en two ' cy pcnlll or want of food In the years 1731 and 173'2 the United Provinces· were under a d de I I. · 1 li · li n h" rea 1U a arm con cernmg t Je c In e~.-Ls, w tch had made great depredation on tile p"l h" h li - h k f Z I · 1 es w IC upport the an s o ea and; but tt was happily difc overcd c f r .n. a 1ew years a terwards that thefe in 1cus had totally abandoned that ifland (DiCt: R ·r - y R - . . ' · auonn e, art. ers ongeurs ) which 1mght have been occafio ned by th ei r not bein e- able to 1· · th 1 · d ' . o tve 111 at autu e when the WuJtcr was rather fcvcrer than ufual. N OT E XXXI.-MAELSTROM. CJ:·tm l b t' broaJ bc/m, t!Je.flutt criltg CalJVaS urge l 'i ·om M,zcljlrow' s }icr·re iJm,tvigablejurge. C A NTO III. 1. 93. ON the coafl: of Norway the re is an cxtcnfivc vortex, or edtly, wh ich lies between the ~ ! lands of Mollo; :-~ nd Molkcn:~s, :~n l is cal led Mofkodhom, or M.1t L!rom; it occ. up c.,; lome leagues in circumferenc ' • and is r.~i d to be very dangcrou and oft en de!l:ructl Vc to vclfds nav igating thcfe fc.1s. ] t is not eafy to underHand the ex illencc of a conl_ l.mt dcf(cnding fhcam without fup pofing it mull pafs through a fubterranean c:tvity to l·>1nc o~hcr p:lrt of the earth or o.::can which may lie bcne:llh its level; as the Mediterr.: wcan Lems t CJ lie beneath the level of the Atlautic oce;:n, which thcrcfQrc con!bntly |