MECHANIC % 
condenfed by cold water. The prefTure of the atmofphere 
would caufe it to enter by all the fuftion-pipes of the dif¬ 
ferent lifts, and prefs on the furface of the water in the 
lower receiver, and force it into the upper one. But, 
becaufe each fuftion-pipe dips in a ciltern of water, the 
air prefles this water before it, raifes it into each of the 
little receivers which it fills, and allows the fpring of the 
air (which was formerly in them, but which now pafles 
up into the lower receiver) to force the water out of the 
lower receiver into the upper one. When this has been 
completed, the fleam is again admitted into the upper re¬ 
ceiver. This allows the water to run back into the lower 
receiver, and the air returns into the fmall receivers in 
the pit, and allows the water to run out of each into its 
proper ciltern. By this means the water of each pipe has 
been railed 15 feet. The operation may thus be repeated 
continually. 
The contrivance is ingenious, and fimilar to thofe which 
are to be met with in the hydraulics of Schottus, Stur- 
mius, and other German writers. But the operation mud 
be exceedingly flow ; and we imagine that the expenfe of 
fleam mud be great, becaufe it mud fill a very large and 
very cold veil'd, which mud wade a great portion of it 
by condenfation. The great defeft of the machine, even 
when we can fecure it againd all rifle of burding, is the 
prodigious wade of deam, and confequently of fuel. Daily 
experience {hows, that a few fcattered drops of cold water 
are fufficient for producing an almod infiantaneous con¬ 
denfation of a great quantity of deam. Therefore when 
the fteain is admitted into the receiver of Savery’s engine, 
and comes into contact with the cold top and cold water, 
tt is condenfed with great rapidity ; and the water does 
not begin to fubfide till its furface has become fo hot that 
it condenfes no more fieam. It may now begin to yield 
to the prefTure of the incumbent deam ; but, as foon as it 
defeends a little, more of the cold furface of the receiver 
comes into contaft with the fleam, and condenfes more 
of it, and the water can defeend no farther till this addi¬ 
tion of cold furface is heated up to the date of evapora¬ 
tion. This rapid condenfation goes on all the while the 
water is defeending. By fome experiments frequently re¬ 
peated by Dr. Robifon, it appears that no lefs than ^-ths 
of the whole fleam is ufelefsly condenfed in this manner, 
and not more than -Jj-th is employed in allowing the wa¬ 
ter to defeend by its own weight; and he has reafon to 
think that the portion thus walled will be confiderably 
greater, if the deam be employed to force the water out 
of the receiver to any confiderable height. It fhould be 
obferved, too, that all this wade mud be repeated in every 
fucceeding ffroke; for the whole receiver mult be cooled 
again in order to fill itfelf with water. 
An attempt was at length made to drain the deep mines 
in Cornwall by a new application of Savery’s engine, for 
which a patent was obtained by Mr. William Blakey, who 
propofed to employ the expanfive force of deam, with an 
intermedium of air between it and the water: this air 
was to ferveas a means of preventing the condenfation of 
the deam, by keeping it from coming in contaft with the 
water. Great contention arofe among fome of thofe who 
counted themfelves men of fcience as to the prafticability 
of fuch a project: fome giving it as their opinion, that, 
if the principle were to be admitted, it would be very 
difficult to apply it in mines, where it would require ten 
atmofpheres at lead : while others, with exalted preten- 
fions, declared it poffible to conduft its influence to the 
centre of the earth. But an accident terminated the 
event as to this engine in Cornwall, by one of the fteam- 
vellels burding through the force of the fleam, though 
much under the degree of power required for the end 
propofed to the Cornifh gentlemen. This being the fird 
date of the application of drong deam to raiding water, 
and, by an eafy tranfition, to do any thing elfe, we have 
given, at fig. 112. a fketch of the boiler and fire-place of 
this engine, copied from the author’s fmall traft on the 
fubjeft, publiihed in French at the Hague in 1776 ; by 
which it will be Teen, that the method of generating fleam 
lately publiihed in the Philofophical Magazine, has been 
made ufe of near forty years ago, and has nearly as long 
fince received its final condemnation : but fuch is the 
degeneracy of man, that, while the Academy of Sciences 
at Paris, and the delegates of the dates-general in Hol¬ 
land, were pluming the author with the gaudied expref- 
fions of their approbation, not one indance can be found 
where he received the encouragement he was led toexpeft. 
But dill this engine is no other than Savery’s engine, 
furnifned with apparatus intended to open and Unit the 
tifual communications by cocks and valves. The fame 
may be faid of Papin’s and Defaguliers’s engines; they 
were all nothing elfe than Savery’s, without the advan¬ 
tage which Blakey had connefted to it; and had nothing 
but a mere nick name to conceal their legitimacy. As to 
the application of the expanfive power of the deam to the 
purpofe fet forth by Mr. Blakey, or indeed we may fay 
by Mr. Savery, it was by no means an irnpoffible thing ; 
but the difficulty would not be here to obtain veffels ca¬ 
pable of refilling the aftion of ten atmofpheres, but how 
to preferve them in a date of fecurity, the decay of veffels 
placed in circumdances like thefe, which cannot be accef- 
fible to the infpeftion of the molt diligent attendant, and 
the conllant anticipation of probable evil circumdances, 
mud render life painful to endure. But there is another 
cafe which ought to be noticed, viz. the difficulty of pre- 
ferving the deam in the degree of temperature by which 
it was generated ; for it is well known that it is conden- 
fible to a very great degree by the common temperature 
indicated by the thermometer; and this extent of ex pail- 
fibility is not to be obtained without the atcelfion of a 
fuperadded quantity of heat. Then, unlefs the veffels in 
which the deam is to operate are kept up to that tempe¬ 
rature, the extra expanfion is annihilated. We have heard 
of patents being pafled for this mode of ufing deam ; but 
we never heard that we were forbidden to ufe deam of 
any particular intenfity, efpecially where cafes quite un- 
expefted have compelled engineers to the prompt ufe of 
it as a necefl'ary expedient; and we fhould imagine that, 
after reading Mr. Watt’s l'pecification of 1769, no perfou 
would attempt a monopoly of the ule of deam at any in¬ 
tenfity whatever. 
2. Mr. Savery having, as we have feen, been engaged 
in projects for draining the tin-mines in Cornwall, the 
principles of his engine became of courfe well known to 
the machiniits and engineers of that and the adjoining 
counties. Among thefe w'ere a Mr. Newcomen, an iron¬ 
monger or blackfmith, and Mr. Cawley, a glazier, at Dart¬ 
mouth, in Devonfhire, who had dabbled much with this 
machine. Newcomen was a perlon of fome reading, and 
was in particular acquainted with the perfon, writings, 
and projefts, of his countryman Dr. Hooke. There are 
to be found among Hooke’s papers, in the poflellion of 
the Royal Society, fome notes of observations, for the ufe 
of Newcomen his countryman, on Papin’s boaded method 
of tranfmitting to a great didance the aftion of a mill by 
means of pipes. Papin’s projeft was to employ the mill to 
work two air-pumps of great diameter. The cylinders of 
thefe pumps were to communicate by means cf pipes with 
equal cylinders furnifhed with piltons, in the neighbour¬ 
hood of a didant mine. Thefe piltons were to be connefted, 
by means of levers, with the pidon-rods of the mine. 
Therefore, when the pidon of the air-pump at the mill 
was drawn up by the mill, the correfponding pidon at 
the fide of the mine would be preffed down by the atmo¬ 
fphere, and thus would raife the pifton-rod in the mine, 
and draw the water. It would appear from thefe notes, 
that Dr. Hooke had diduaded Mr. Newcomen from erect¬ 
ing a machine on this principle, of which he had expofed 
the fallacy in feveral difeourfes before the Royal Society. 
One paflage is remarkable: “ Could he (meaning Papin) 
make a fpeedy vacuum under your fecond pidon, your 
work is done.” 
It is highly probable that, in the courfe of this fpecu- 
5 lation. 
