iraUl-- Spouts. HAihults of Light: 585 



tlic letter c it may be obferyed how the protuberance b having arrived over the foot a be- 

 came vertical, and unrolled itfelf inftantly in a kind of large bag, of the figure of an inverted 

 cone, nearly tranfparent, like gauze. As foon as this bag compofed of the matter of the 

 cloud had developed itfelf, which occupied the time of three or four feconds, and had fixed 

 lis fmall extremity in the bottom of the foot d, it became (traight, without folds. A vapour 

 like that feen in 1 7S0 immediately rofe up the tube, extended it in the form of a water-fpout, 

 deprived it of its tranfparency, gave it a deep indigo-colour, like that of the clouds, and at 

 the fame inftant the foot and the fpout were moved from call to weft, and followed the 

 courfe which the impulfe of the wind gave to the clouds to which the fpout was attached. 

 This fpout being deftroyed, the following fpout exhibited the fame phenomena as the others. 

 It muft be remarked, that the diftance of the protuberance b from the foot already formed 

 at a could not be augmented in the figBre ; but this protuberance, when firft obferved, was 

 at more than a league diftant from a, which remained motionlufs till its arrival. It is pro- 

 bable that it may have arrived from a ftill greater diftance. It is alfo to be noted, that the 

 fpouts 2 and 3 were fomewhat lefs in all their dimcnfions than the firft. ' 



Fig. 4. exhibits two water-fpouts, which were feen following each other on the 19th of 

 March. The wind was lefs ftrong than on the 6th of Januaiy, the fea lefs agitated, the 

 clouds lefs accumulated, and lefs deep in colour. The intenfity of the phenomenon 'was 

 alfo proportionally lefs. It may be feen at a and b that the furroundlng plumes of the 

 foot had not the power to raife themfelves up, as in the preceding figures, but were kept 

 down by the wind. The enlargement of the upper part of the fpout d appeared to be n 

 commencement of diflblution, fuch as was obferved at b fig. 2. Thefe two water-fpout* 

 proceeded to the point of N. Dame de la Garde, beyond Antibes. Thofc of the 6th of 

 January reached the fliore between the town of Antibes and the mouth of the Var. The 

 line they defcrlbed from the time we firft faw them to that of reaching the (hore may be 

 <fUmated at five or fix common leagues. 



Advcrtifement refpeBlng the Figures. 

 THE. magnitude of fig. i. in thefe drawings muft not be confidercd as proportional to 

 fliofe of the figures 2, 3, 4. The firft water-fpout pafTed at no greater diftince th»n a 

 mufket-fliot from our windows ; the others were at the diftance of two or three leagues. 

 It Is neceflary to make allowance for what the firft gained by its nearnefs, and the other* 

 loft by their remote fituation, In order to form a judgment of the refpedive fize of cacli 

 fuppofed to be at the fame diftance. 



II. 



Experiments and Obfirvntions on the Infeshn, Rejlexion, and Colours of Light. 

 By H£NHr Brougham, Jan. Efq. 



[ConcluJciJ from page 5^3-j 



Irl AVING endeavoured to unfold the property of flexibility, as varied in inflexion, de- 

 flexion and reflexion ; and alfo the phyficnl caufe of this property; and having indulged in 

 » fpcculation depending on this caufe, I flatter myfclf neither altogether ufclcfs nor unim- 

 V0L.I.— Makch J798.-Si'pri,. 4F portant i 



