"MECHANIC S. 
*75i 
with the bucket D working in it 5 E is the clack, (alfo 
fliown enlarged in figs. 79 and 80.) F is the fuftion-pipe, 
and GG a moveable lengthening-piece ; this Hides over 
and includes the other when the pump is firll fixed ; but, 
as the pit is funic, it Aides down over the pipe F, to reach 
the bottom. The outfide of the inner-pipe, F, is turned 
truly cylindrical and fmooth; and the infide of the outer 
pipe G, at the upper end, for about fix inches down, is 
made to fit it. The junction is made perfect:, by leathers 
being placed in the bottom of the cup a a, which holds 
water and wet clay over them, to keep them wet and plia¬ 
ble, and confequently air-tight. The lower extremity of 
the fuftion-pipe G terminates in a rrofe R, pierced with a 
number of f'mall holes, that it may not take up dirt. 
This nofe is not placed in a line with the pipe, but-curved 
to one fide of it, like a crank, fo as to defcribe a circle 
when turned round. By this means the miners, by turn¬ 
ing it round upon the pipe F, can always place the nofe R 
in the deepeft part of the pit; and, when they dig or 
blaft a deeper part, they turn the nofe about into it, the 
Hiding-tube lengthening down to reach the bottom of the 
hole, as lhawn in the figure. By this means there is never 
a necefiity to fet a fhot, for blalting»fo near the pump-foot 
as to put it in any danger of being injured by the explo- 
fion, as is the cafe in the common pump, in which this 
danger can only be avoided by moving the punvp-foot to 
one fide of the pit, which neceflarily throws the whole 
column of pumps out of the perpendicular. 
The coniiruction of the clack is explained by figs. 79 
and 80. the former being a feftion, and the latter a plan. 
LL is a caff-iron ring, fitting into a conical feat in the 
bottom of the chamber of the pump ; it has two ffems, /, /, 
jrifing from it, to fupport a fecond iron-ring M M ; juft 
beneath this, a bar, m, extends acrofs from one Item to 
another, and has two fcrews tapped through it ; thefe 
prefs down a fecond crofs-bar n, which holds the leather 
of the vahves down upon the crofs-bar of the ring L, and 
this makes it fit ft, forming the hinge on which the double 
valves open, without the necefiity of making any holes 
through the leather, as is common ; but the chief ad¬ 
vantage is, that by this means the clack can be repaired, 
and a new leather put in, with very little lofs of time, an 
objeft of the greateft importance; for in many fituations 
the water gathers fo faff in the pit, that, if the clack fails, 
and cannot be quickly repaired, the water rifes above the 
clack-door, fo as to prevent any accefs to it; and there is 
no remedy, in the common pump, but drawing up the 
whole pile of pumps, which is a mofl tedious and ex- 
penfive operation. In Mr. Brunton’s pump, the clack 
can at any time be drawn out of it, by firft drawing out 
the bucket, and letting down an iron prong, fig. 3 r. which 
has hooks on the outfide of its two points : this, when 
dropped down, will fall into the ring M, and its prongs 
fpringing out will catch the under fide, and hold it fait 
enough to draw it up. 
Another part of Mr. Brunton’s improvement confifis 
jn the addition of a pipe H, (fig. 78.) which is caft at the 
time time with the barrel, and communicates with it at 
the top and bottom, juft above the clack ; at the upper end 
the pipe is covered by a Hat Aiding-plate, which can be 
moved by a fmall rod b, palling through a collar of lea¬ 
ther ; the rod has a communication by a lever, fo that the 
valve can be opened or fhut by the men in the bottom of 
the pit. The object of this fide-pipe is to let dow-n fuch 
a proportion of the water which the pump draws, as will 
prevent it from drawing air; though, of courfe, the mo¬ 
tion of the engine will be fo adapted as not to require a 
great proportion of the water to he thus returned through 
the fide-pipe, yet it will not be pofiible to work the en¬ 
gine fo correctly as not to draw fome without this con¬ 
trivance ; and, if it does, it draws up dirt and pieces of 
Hone into the pump, befides caufing the engine to work 
very irregularly, in c.onfequence of partially loling its 
load every time the air enters the pump. Another ufe of 
the fide-pipe is to letdown water into.the chamber of the 
clack to fill it, when the engine Is firft fet to work, after 
the pumps have been (landing (till, and the lower part of 1 
the barrel and chamber empty. For this invention, the 
Society prefented Mr. Brunton with their filver medal, in 
1811. 
Among the perils of a fea-faring life, a leaking Arip may 
be reckoned the moll dreadful and fatal of all others ; 
here not only one man, or a few men, perifh, but every 
living creature on-board. When a fiiip ilrikes againfl a 
rock, and is wrecked, fome lives may be faved by float¬ 
ing planks and rigging ; if the magazine takes fire, death 
comes inftantaneoufly, and kills, perhaps, in the moll 
gentle manner; but in the defperate cafe of a leak, how 
llowiy does the awful monarch advance, attended by all 
the terrors of anxious fufpenfe. In fuch a melancholy 
fltuation, all hopes and expectations for help and fafety 
mult be placed in the pumps ; and this confideration ren¬ 
ders thole machines of vail eftimation and confequence ; 
it highly imports every commander of a fiiip (to whom the 
lives of his men are committed) to take the utinoft care 
that his (hip be fupplied with fuch pumps as will belt pro¬ 
vide againlt, and ward off - , thefe impending dangers. By 
any negligence in this refpeft, he may become guilty of de- 
Itroying his own life, the lives of his men, and of the ruin 
and milery of many families; it therefore becomes his duty 
to be furnilhed with the belt pump that can be procured 
for evacuating the hold from the water that may at any 
time get in, with the leaft force, and in the (horteft time. 
At different times, almoft every defeription of pump 
has been employed in lhip-fervice; but cuftom has at 
length dicided in favour of the chain-pump, although, from 
the friftion naturally attending its conltruflion, it takes 
femewhat more power to raife a certain quantity of water 
than fome other kind of pumps when well made. Yet on, 
the whole, from being fo little liable to choke up or be de¬ 
ranged by violent ufe, it has gained the preference among 
feamen. Conltant attempts have been made to produce a 
pump that would raife a greater quantity of water than tha 
chain-pump with the fame power, and Itill to preferve tha 
other advantages of that machine. Thefe inventions hava 
been offered to the public one after another, with pompous 
recommendations by their refpeftive projectors, who hava 
never failed to report their effects as conliderahly fuperior 
to that of other pumps with which they have been tried. 
It is, however, much to be regretted, that in thefe forts of 
trials there is not always a Icrupulous attention to whaJ 
may be called mechanical juftice. The artift who wilhes 
to introduce a new piece of mechanifm, has generally 
fufficient addrefs to compare its effects with one of the 
former machines which is crazy, or out of repair; a re¬ 
port of this kind, indeed, favours Itronglyof the evidence 
of a falfe witnefs ; but this finefl'e is not always difeo- 
vered. The perfor.s appointed to fuperintend the com¬ 
parative effect of the different pumps, have not always h 
competent knowledge of hydraulics to detect thefe arti¬ 
fices, or to remark, with precifion, the defefls and ad¬ 
vantages of thofe machines, as oppofed to each other. 
Thus, the feveral inventions propofed to fuppiant the 
chain-pumps which are now generally ufed in the Britifu 
navy, have hitherto proved ineffectual, and are no longer 
remembered. 
In many inftances, for want of a proper knowledge of 
mechanics and hydraulics, thefe inventions have pro¬ 
ceeded upon a miltaken principle, fuppofing it pofiible to 
make fome contrivance or other, by which a pump rtiouid 
raife more water with a certain power than has ever been 
done before. This is a miltaken idea; for pumps, in 
point of the quantity of water they will raife, have,long 
ago been brought to as great a degree of perfection as it is 
perhaps pofiible ; and to raife a greater weight of water 
than the power applied is equal to, is an impoflibility, as 
no power or effort can really be iucreafed by any kind o? 
machinery, it can only be modified ; and what is gained 
in the magnitude of the effeft the machine produces, is loll 
in the time expended to accomplifit it; in truth, rather 
. jnors 
