and 'tis fiofiting IJlands. \S^ 



a few fcconds about two inches high, occafioned by the air 

 that followed tlic hook out. ■, 



The riiina: of thcfe iflands, is alyvays accompanied with a 

 botioiii wind : vet the bottom wind aiipears frequcnl'v with- 

 out theni ; and generallv afl^r'a. mpulh or fix sveeks of dry 

 Weather the lake is foineliinies oartialjy, fonietimes wholly 

 agitated, accompanied !>v a roaring uoife (the probable cf- 

 fe-ols of echo in a calm in that iiiualio:?.). The waves are not 

 Jong and rolling, but iri.egujar tliaped like mountains, ap 

 inches to two feet in height, like water jumbled in a tub j 

 thev frc(iuciitlv llrike .the .boat likca.rock, and break in fpray 

 from hei.d to Item,- Vi^'t always when it is perfedly calm, but 

 alfo wkii a gentle breeze, barely enough to ripple the furfacc. 

 Thev ^queutiy indicate a change of weather from fair to 

 i-ain, and the grcatell degree of agitation is always in the 

 deepelt water. 



Having thus minujtc'y defcribed all the particulars I have 

 time to collet'l. I fliall leave it to otheis to fmd a better ex- 

 planation than the following. When we conlider that half 

 the bottom of ihe lake is covered with a tine uuid impervious 

 to air, reftm<T I'pon half-putrid vegetable matter; that being 

 attached to the Hoping b.inks. all air thai, is generated will 

 endeavour to rife to the highcit part, but cannotuhen get out; 

 that great part of the bottom is a clean bed of pcl)bles and 

 Hone- pervious to air ; that the iflands begin to 'ife generally 

 in fiom 9 ui 12 fett WdCer, and arc of o«n(iderab!e furtlice; 

 that the^ have been mealured 21 feet thick, with clear water 

 under them ; and that the rnqft violent efte6ts have been in 

 the fumnier iiioiiths — Is il not probabit thai the ^lir let at 

 hbciu- by putrefa^non is enough to raife thefe large maiTes, 

 fo thick, anni "fo little heavier than water ilielf; to contra6t 

 ani-1 expand their e.uremities enough to give the violent and 

 irKguljr motion to the fupernieumbent waters, by their 

 flownig oriT, their reflux, and iheir bre^iking through — ^t^^l ihat, 

 more or leG, wlieihcr thev rife to thu furfacc, or only part of 

 tht way, to Imd their equ-libriuni in the furrounding fluid ? 

 WiP.iing our ignorance «f the cau,fe of this ciiriofily of our 

 own country may f >on be removed^ and wi(l4ing fuccefs to 

 cvciv inieftigaiion of tlic pha'uomena of nature, I will con- 

 clude with the iignature of 



D. I. P. 



L 3 XXIX. Dtf- 



