I'l!' PIPE. 



Carnarvonshire. Early in life, she was distinguished 

 in the fashionable world by her beauty and accom- 

 plishments. In 1763, she was married to Uenry 

 Thnile, a brewer of great opulence in Southwark, 

 which borough he then represented in parliament. 

 Soon after commenced her acquaintance with doctor 

 Johnson, of whom she published Anecdotes, in one 

 octavo volume (178b). Mr Thrale dying in 1781, 

 his widow married, in 1784, Piozzi, a Florentine 

 music master. She accompanied her husband to his 

 native city. Among her writings are, Observations 

 made in France, Italy, and Germany (1789) ; British 

 Synomymy, or an Attempt at regulating the Choice 

 of Words in familiar Conversation (1794) ; Review 

 of the most striking Events and Characters of the 

 last 1800 Years (1801), &c. Mrs Piozzi died at Clif- 

 ton, May 2, 1821, in her 82d year. 



PI P, OR PEP (pepia) ; a disease among poultry, 

 consisting of a while, thin skin, or film, that grows 

 under the tip of the tongue, and hinders their feeding. 



PIPE, in law ; a roll in the exchequer, otherwise 

 called the great roll ; whence there is an office called 

 the pipe-office, where cognizance is taken of forfeitures 

 to the king. 



PIPE ; a wine measure, usually containing from 

 110 to 140 gallons. Two pipes, or 252 gallons, 

 make a tun. 



PIPE. We have given a view of the general laws 

 of the motions of liquids in the article Hydrodynamics, 

 but there are some practical results of these laws, as 

 applied to their motions in pipes, which derive im- 

 portance from the great use made of pipes in the 

 conveyance of water. (See Aqueducts.) The fric- 

 tion that occurs between a solid and the surface upon 

 which it moves can be accurately ascertained but 

 not so with a fluid ; for in this, while one part may 

 be moving rapidly, another may be quite stationary, 

 moving slowly, or even moving in a contrary direc- 

 tion. This is particularly observable in rivers, where 

 the central part, or main current, will always be 

 found flowing with much greater rapidity than either 

 side ; and experiment proves that the same effect 

 occurs when water flows through pipes ; for that 

 water, which is in contact with the side of the pipe, 

 moves with much more resistance than that at the 

 centre, whereby the calculated discharge of any 

 given pipe of considerable length, becomes much less 

 than is due to its magnitude. The term friction is 

 applied to this obstruction to the passage of fluids, in 

 the same manner as it is to solids, and it exists to 

 such an extent as to become an object of considerable 

 inconvenience in practice. It can only be obviated 

 by making the conveying pipe of much larger dimen- 

 sions than would otherwise be necessary, so as to 

 allow the free passage of a sufficient quantity of fluid 

 through the centre of the pipe, while a ring or hollow 

 cylinder of water is considered to be nearly at rest 

 all around it. Other circumstances besides friction 

 likewise tend to diminish the quantity of fluid which 

 would otherwise pass through pipes, such as the 

 existence of sharp or right-angled turns in them, and 

 permitting eddies or currents to be formed, or not 

 providing for the eddies that form naturally, by suit- 

 ing the shape of the pipe to them. It follows, there- 

 fore, that whenever a bend or turn is necessary in a 

 water pipe, it should be made in as gradual a curve 

 or sweep as possible, instead of the form of an acute 

 or even right angle ; that the pipe should not only 

 be sufficiently capacious to afford the necessary sup- 

 ply, but should be of an equal bore throughout, and 

 free from all projections or irregularities, against 

 which the water can strike and form eddies or rever- 

 berations, since these will impede the progress of the 

 fluid as effectually as the most solid obstacles. The 

 friction of water in channels or pipes has been found 



to increase as the square of the velocity. It has also 

 been found that the form of the t-nd of the pipe 

 which conimunicates with the fountain-head, or re- 

 servoir, greatly affects the quantity of water received 

 by it. If it be gradually enlarged like a trumpet 

 mouth, a larger quantity of water will be received 

 than by any of the modes which follow, because the 

 direction given to the particles by this form is most 

 favourable to their admission. If the entrance to the 

 pipe be abrupt, in consequence of the cavity being 

 wholly cylindrical, the particles will have a tendency 

 to cross each other, and less water will enter the 

 pipe in a given time. And if the end of the pipe 

 projects into the reservoir, a variety of opposing 

 forces will be produced among the particles moving 

 towards the entrance, so that a smaller quantity will 

 be received by the pipe, than in either ot the preced- 

 ing cases. The form of the discharging orifice, like- 

 wise, influences the quantity of water delivered by 

 a pipe in a given time. If the end of the pipe be 

 enlarged, by adding to it a frustum of a hollow cone, 

 the amount of water discharged in some cases may 

 be prodigiously increased. This fact, described by 

 Venturi, appears to be the result of the pressure of 

 the atmosphere, aided by the inertia and cohesiveness 

 of the water. The pipes by which water is conveyed 

 beneath the ground are generally of small or mod- 

 erate size, are intended to be water tight, and have 

 been made from a great variety of materials. It is 

 desirable that they should possess strength, tightness 

 and durability, and that the material of which they 

 are composed should not be capable of contaminating 

 the water. 



Wooden pipes are commonly hollow logs, perforated 

 by boring through their axis, and connected by mak- 

 ing the end of one log conical, and inserting it into a 

 conical cavity in the next. Wooden pipes are in 

 common use in this country, but are liable to dt^eay, 

 especially at the joints, where their thickness is 

 smallest. 



Iron pipes are considered preferable to those of 

 wood, being stronger, and, in most situations, more 

 durable. They are made of cast iron, with a soc- 

 ket, or enlarged cavity at one end, into which the 

 end of the next pipe is received. The joints thus 

 formed are rendered tight, either by filling the inters- 

 tices with lead, or by driving in a small quantity of 

 hemp, and filling the remainder of the socket with 

 iron cement, made of sulphur, muriate of ammonia, 

 and chippings of iron. 



Copper pipes are extremely durable, and are made 

 of sheet copper, with the edge turned up and soldei- 

 ed. They require to be tinned inside, on account of 

 the poisonous character of some of the compounds 

 which are liable to be formed in them. 



Lead pipes are much employed for snail aqueducts, 

 owing to the facility with which they can be soldered, 

 and bent in any direction. They are commonly cast 

 in short pieces, and afterwards elongated by drawing 

 them through holes, in the same manner as wire. 

 Leaden pipes, in general, are supposed not to conta- 

 minate the water contained in them, because the car 

 bonate of lead, which is sometimes formed in them, 

 is insoluble in water. They are not safe, however, 

 for pumps and pipes intended to convey acid liquors. 



Stone pipes preserve the water contained by them 

 in a very pure state. They are, however, expensive, 

 on account of the labour of working them, with the 

 exception of soap stone, which, being readily shaped 

 and bored, may be usefully applied for the purpose 

 of conveying water, in those places where it is easily 

 procured. 



Earthen pipes, made of common pottery wnre, and 

 glazed on the inside, are sometimes used, but are 

 more liable to be broken than most of the other kinds. 



