General Rcjulu of hydraulic Experiments. 59 



their variety of compofition, are continually producing changes which the art of the chemiit 

 !S unable to imitate. Though the chemlft, at prefent, can extend his power no further by the 

 fimple r.ttra6lions and repulfive motions of inorganic matter, yet a path of fcience, difplaying 

 a boundlefs field for inveftigation, feems now opan in the changes efFeSted in dead matter 

 by living beings. By difcovering tliofc changes, we might go far towards difcovering the 

 laws of their organization. 



IV. 



Jua/ytical Talk of the Refults of the Courfe of Experiments on the lateral Communication of 

 Motion in Fluids. By Citizen J. B. VeKTUJRE, Profeffor of experimental PhUofopky at 

 Modena, i^c. drawn up hy the author himfdf *. 



D, 



'ESCRIPTION of the apparatus, page 172 — It is proper to miftru ft all theories of 

 Hydraulics, not excepting that which is exhibited in the prefent work, excepting fo far as 

 thofe theories maybe fupported by experiment, p. 173. 



In any fluid, thofe parts which are in motion carry along with them the lateral parts which 

 are at reft. Prop. I. exper. i. ibid. — I call this phenomenon /^^ lateral communication of motion; 

 and I confider it as a principle of experiment, or elementary faft, without explaining its caufe, 

 174. — If water be drawn out of a veffel by an horizontal cylindrical pipe, of which the part 

 neareft the veflel is contrafted according to the form of the contradled vein of water which 

 flows through an equal orifice in a thin plate, the expenditure will be increafed by this pipe, 

 in the fame rnanner as if there had been no contrailion. Prop. II. exper. 3 and 4. ibid. — 

 The velocity of the flream, within this tube, is greater than that^of the jet through a thin 

 plate, p. 175. — The increafe of expenditure of water through an horizontal cylindrical pipe, 

 whether it be of uniform diameter throughout or contraded at the end next the refervoir, is 

 caufed by the prefTure of the atmofphere. Prop. III. exper. 5, 6, 7, ibid. — This increafe of 

 expenditure, through a pipe, does not take place in the vacuum of the air pump. Exper. 8. 



P- 176- ... . -' 



When water is drawn through a defcending cylindrical tube, of which the upper part is of 



a divergent form, anfwerable to that of the contradted vein, the expenditure will be 

 that which is anfwerable to the height of the charge above the lower orifice of the tube. 

 Reftification of the theory afTerted on this fubjeft by Guillielmini, and adopted by various 

 philofophers. — Experiments, prop. IV. exper. 9, 10, 11, 12. p. 178. — The lateral commu- 

 nication, of motion in fluids is rhe caufe which excites the preffure of the atmofphere 

 to increafe the expenditure and internal velocity in horizontal conical tubes of a certain form. 

 Prop. V. p. 273. — Experiments relative to this augmentation — the refult always falls fhort 



• And fubjoined to his treatife. — The paginal numbers refer to the fecond volume of this JcuvmI, except 

 ^vhcre the Number III. is prefixed) which of courfe implies the prefent volume. 



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