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pressure in fluids; as exhibited in the well known 'hydrostatic

paradox。' In his patent of 1785; in which he no longer describes

himself as Cabinet maker; but 'Engine maker' of Piccadilly; he

indicated many inventions; though none of them came into practical

use;such as a Hydrostatical Machine and Boiler; and the application

of the power produced by them to the drawing of carriages; and the

propelling of ships by a paddle…wheel fixed in the stern of the

vessel; of which drawings are annexed to the specification; but it

was not until 1795 that he patented his Hydrostatic or Hydraulic

Press。



Though the principle on which the Hydraulic Press is founded had long

been known; and formed the subject of much curious speculation; it

remained unproductive of results until a comparatively recent period;

when the idea occurred of applying it to mechanical purposes。  A

machine of the kind was indeed proposed by Pascal; the eminent

philosopher; in 1664; but more than a century elapsed before the

difficulties in the way of its construction were satisfactorily

overcome。  Bramah's machine consists of a large and massive cylinder;

in which there works an accurately…fitted solid piston or plunger。  A

forcing…pump of very small bore communicates with the bottom of the

cylinder; and by the action of the pump…handle or lever; exceeding

small quantities of water are forced in succession beneath the piston

in the large cylinder; thus gradually raising it up; and compressing

bodies whose bulk or volume it is intended to reduce。  Hence it is

most commonly used as a packing…press; being superior to every other

contrivance of the kind that has yet been invented; and though

exercising a prodigious force; it is so easily managed that a boy can

work it。  The machine has been employed on many extraordinary

occasions in preference to other methods of applying power。  Thus

Robert Stephenson used it to hoist the gigantic tubes of the

Britannia Bridge into their bed;*

 'footnote。。。

The weight raised by a single press at the Britannia Bridge was 1144

tons。

 。。。'

and Brunel to launch the Great Eastern steamship from her cradles。  It

has also been used to cut bars of iron; to draw the piles driven in

forming coffer dams; and to wrench up trees by the roots; all of

which feats it accomplishes with comparative ease。



The principal difficulty experienced in constructing the hydraulic

press before the time of Bramah arose from the tremendous pressure

exercised by the pump; which forced the water through between the

solid piston and the side of the cylinder in which it worked in such

quantities as to render the press useless for practical purposes。

Bramah himself was at first completely baffled by this difficulty。  It

will be observed that the problem was to secure a joint sufficiently

free to let the piston slide up through it; and at the same time so

water…tight as to withstand the internal force of the pump。  These two

conditions seemed so conflicting that Bramah was almost at his wit's

end; and for a time despaired of being able to bring the machine to a

state of practical efficiency。  None but those who have occupied

themselves in the laborious and often profitless task of helping the

world to new and useful machines can have any idea of the tantalizing

anxiety which arises from the apparently petty stumbling…blocks which

for awhile impede the realization of a great idea in mechanical

invention。  Such was the case with the water…tight arrangement in the

hydraulic press。  In his early experiments; Bramah tried the expedient

of the ordinary stuffing…box for the purpose of securing the required

water tightness' That is; a coil of hemp on leather washers was

placed in a recess; so as to fit tightly round the moving ram or

piston; and it was further held in its place by means of a

compressing collar forced hard down by strong screws。  The defect of

this arrangement was; that; even supposing the packing could be made

sufficiently tight to resist the passage of the water urged by the

tremendous pressure from beneath; such was the grip which the

compressed material took of the ram of the press; that it could not

be got to return down after the water pressure had been removed。



In this dilemma; Bramah's ever…ready workman; Henry Maudslay; came to

his rescue。  The happy idea occurred to him of employing the pressure

of the water itself to give the requisite water…tightness to the

collar。  It was a flash of common…sense genius beautiful through its

very simplicity。  The result was Maudslay's self…tightening collar;

the action of which a few words of description will render easily

intelligible。  A collar of sound leather; the convex side upwards and

the concave downwards; was fitted into the recess turned out in the

neck of the press…cylinder; at the place formerly used as a

stuffing…box 。  Immediately on the high pressure water being turned

on; it forced its way into the leathern concavity and 'flapped out'

the bent edges of the collar; and; in so doing; caused the leather to

apply itself to the surface of the rising ram with a degree of

closeness and tightness so as to seal up the joint the closer exactly

in proportion to the pressure of the water in its tendency to escape。

On the other hand; the moment the  pressure was let off and the ram

desired to return; the collar collapsed and the ram slid gently down;

perfectly free and yet perfectly water…tight。  Thus; the former

tendency of the water to escape by the side of the piston was by this

most simple and elegant self…adjusting contrivance made instrumental

to the perfectly efficient action of the machine; and from the moment

of its invention the hydraulic press took its place as one of the

grandest agents for exercising power in a concentrated and tranquil

form。



Bramah continued his useful labours as an inventor for many years。

His study of the principles of hydraulics; in the course of his

invention of the press; enabled him to introduce many valuable

improvements in pumping…machinery。  By varying the form of the piston

and cylinder he was enabled to obtain a rotary motion;*

 'footnote。。。

Dr。 Thomas Young; in his article on Bramah in the Encyclopaedia

Britannica; describes the 〃rotative principle〃 as consisting in

making the part which acts immediately on the water in the form of a

slider; 〃sweeping round a cylindrical cavity; and kept in its place

by means of an eccentric groove; a contrivance which was probably

Bramah's own invention; but which had been before described; in a

form nearly similar; by Ramelli; Canalleri; Amontons; Prince Rupert;

and Dr。 Hooke。

 。。。'

which he advantageously applied to many purposes。  Thus he adopted it

in the well known fire…engine; the use of which has almost become

universal。  Another popular machine of his is the beer…pump; patented

in 1797; by which the publican is enabled to raise from the casks in

the cellar beneath; the various liquors sold by him over the counter。

He also took out several patents for the improvement of the

steam…engine; in which; however; Watt left little room for other

inventors; and hence Bramah seems to have entertained a grudge

against Watt; which broke out fiercely in the evidence given by him

in the case of Boulton and Watt versus Hornblower and Maberly; tried

in December 1796。  On that occasion his temper seems to have got the

better of his judgment; and he was cut short by the judge in the

attempt which he then made to submit the contents of the pamphlet

subsequently published by him in the form of a letter to the judge

before whom the case was tried。*

 'footnote。。。

A Letter to the Right Hon。  Sir James Eyre; Lord Chief Justice

of the Common Pleas; on the subject of the cause Boulton and

Watt v。 Hornblower and Maberly; for Infringement on Mr。 Watt's Patent

for an Improvement of the Steam Engine。  By Joseph Bramah; Engineer。

London; 1797。

 。。。'

In that pamphlet he argued that Watt's specification had no definite

meaning; that it was inconsistent and absurd; and could not possibly

be understood; that the proposal to work steam…engines on the

principle of condensation was entirely fallacious; that Watt's method

of packing the piston was 〃monstrous stupidity;〃 that the engines of

Newcomen (since entirely superseded) were infinitely superior; in all

respects; to those of Watt; conclusions which; we need scarcely

say; have been refuted by the experience of nearly a century。



On the expiry of Boulton and Watt's patent; Bramah introduced several

valuable improvements in the details of the condensing engine; which

had by that time become an established power;the most important of

which was his 〃four…way cock;〃 which he so arranged as to revolve

continuously instead of alternately; thus insuring greater precision

with considerably less wear of parts。  In the same patent by which he

secured this invention in 1801; he also proposed sundry impro

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