-l<ji' Experiments an the lateral Communicalm »f Motion in Fluids, 



In the melted greafe which lies round the wick of a common candle, when lighted, thers 

 are fometimes obferved atoms, which have been left by the fnuffers, moving to and from the 

 flame continually. Thefe motions have been conceived by fome as occafioned by attrac- 

 tions and repulfions, in confequence of an eleiSlrical quality imputed to the flame. It fhoiilJ 

 feem, however, that they depend merely upon oppofite currents, at the furface and imme- 

 diately below the furface of the melted greafe, according to the principle above explained. 



VII. 



Experimental Refearches concerning the Principle of the lateral Communication of Motion in 

 Fluids, applied to the Explanation of various Hydraulic Phenomena. By Citizen J. B. 

 VenTVRI, Profejfor of Experimental Philofcphy at Modena., Member of the Italian Society 

 of the Injiitute of Bologna, the Agrarian Society of Turin, is'c* 



HE apparatus made ufe of in mod of the following experiments is the fame as that of 

 Poleni t- It is reprefentedatFig. i. Pi. VIII. The refervoir X, of a conical form, has forty 

 inches diameter at CE, and 30 at O P. F P is a broad plate of copper, the plane of which 

 is perpendicular to the horizon ; it is applied to the infide of the refervoir. The valve or 

 flap rS, moveable by the handle K, is drawn up againfl: the fide of the veflel above F, in 

 order that it may not impede the courfe of the particles of the fluid contained in the refer- 

 vo>f to the aperture P. I have applied different ajutages to this aperture, according to the 

 exigence of the cafe. The tubes which I applied were made of tinned iron of the beft 

 quality ; the longitudinal jun£lion of the edges was made by immediate contadl, and not by 

 overlapping, and the whole of the workmanfhip was executed with great care. When the 

 aperture was fimply a hole through a thin plate, the thicknefs of its edge did not exceed one 

 fourth of a line. 



The upper vefi"el Z ferves to maintain the water of the refervoir X at the conftant height 

 of the line C E, while it flows out through P. The plug A B is drawn more or lefs back, 

 in order to regulate the introduction of the fupply. The box or flielf D L prevents this 

 water from exciting by its fall any agitation which might influence the emilTun at P. The 

 opening at Q.difcharges the fuperfluous water which might rife above the line C E. The 

 height of the furface C E above the centre of the orifice at P was 32,5 inches, in all cafes 

 where it is not otherwife exprefled. 



Mod of the expetimcnts here defcribed were made in public at the Philofophical Theatre 

 of Modena ; various men of fcience were prefent at the reft j the diflFerent departments of 

 experiment were i>erformed by feveral perfons at the fame time. One of thefe operators re- 

 peated the fcconds audibly from the clock ; another drew back the valve S F; a third regu- 

 lated by the means of the plug B the introduftion of the fupply of water, fo that a very thin 



• Since the receipt of this memoir (which is equally valuable as the fource of data for fcientific proceffes, 

 and of ufcful praaical relults, tiiher unknown or dfreganled in hydraolic works) it has reniained in my hands 

 with the intention of prefcnting my readers with an abftraft of its contents. But, upon ftriacr confideration,. 

 1 have thought it beft to give it entire from the French original. N. 



f De Caftellis. This treatife is reprinted in the third volume of Hydraulic Treaties, publiflicd at Parma. V, 



6 fheet 



