A METHOD AND APPARATUS FOR CONTINUALLY CHANGING THE WATER USED IN BOILERS FOR GENERATING- STRAM, PARTICULARLY APPLICABLE TO THE BOILERS OF STEAM VESSELS MAKING LONG VOYAGES, BY PREVENTING THE DEPOSITION OF SALT OR OTHER SUBSTANCES CONTAINED IN THE WATER, AT THE SAME TIME RETAINING THE HEAT, SAVING FUEL, AND RENDERING THE BOILERS MORE LASTING
Year: 1824

page_text: MAUDSKA I
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
MAUDSLAY and JOSHUA FIELD, both of Lambeth, in the County of Surrey,
Engineers, send greeting.
WHEREAS His present most Excellent Majesty King George the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing
date at Westminster, the Fourteenth day of October, in the fifth year of His
reign, did, for Himself, His heirs and successors, give and grant unto us, the
said Henry Maudslay and Joshua Field, His especial licence, that we, the
said Henry Maudslay and Joshua Field, their exors, admors, and assigns, or
such others as we, the said Henry Maudslay and Joshua Field, our exors,
admors, and assigns, should at any time agree with, and no others, from time
to time and at all times during the term of years therein expressed, should and
lawfully might make, use, exercise, and vend, within England, Wales, and
the Town of Berwick-upon-Tweed, our Invention of "A METHOD AND APPARATUS
FOR CONTINUALLY CHANGING THE WATER USED IN BOILERS FOR GENERATING- STRAM,
PARTICULARLY APPLICABLE TO THE BOILERS OF STEAM VESSELS MAKING LONG VOYAGES,
BY PREVENTING THE DEPOSITION OF SALT OR OTHER SUBSTANCES CONTAINED IN THE
WATER, AT THE SAME TIME RETAINING THE HEAT, SAVING FUEL, AND RENDERING THE
BOILERS MORE LASTING;" in which said Letters Patent there is contained a
proviso obliging us, the said Henry Maudslay and Joshua Field, by an instru-
ment in writing under the hands and seals of us, or under the hand and seal of
one of us, particularly to describe and ascertain the nature of our said Invention,
and in what manner the same is to be performed, and to cause the same to

page_text: be enrolled in His Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited Letters
Patent, (as in and by the same,) reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Joshua Field, do hereby declare that the nature of our said Invention, and
the manner in which the same is to be porformed, are particularly described and
ascertained in the following description thereof (that is to say):-
:-
It consists, in the first place, of an apparatus for effecting a constant and
uniform change of the water used in the boilers of steam vessels or other
boilers working with sea or salt water, by which a quantity of brine is constantly
withdrawn from the boiler, bearing any given proportion to the quantity of water
evaporated in the production of steam, so that the brine in the boiler can
never exceed a limited degree of concentration proportional to the quantity so
withdrawn from twenty to thirty per cent. of the quantity evaporated taken
out will keep the water within a degree of saltness from which no practical
evils can result, however long the boiling be continued. Our method of
effecting this object is by using meters of any kind that will regulate and
adjust the quantity withdrawn to the quantity evaporated or distilled over in
the form of steam. The meter we most prefer is a small pump with a loaded
discharge valve, worked by the engine, and so proportioned as to draw from
the lowest part of the boiler the quantity determined upon. If, for instance,
twenty-five per cent., or one fourth the total evaporation, be the quantity
withdrawn, it will be equal to one fifth the quantity of common sea water
driven into the boiler to keep up the supply; then as sea water contains about
one thirty-second part of salt, the water of the boiler will slowly but ultimately
attain a degree of saltness equal to 5/32 or 4/32 parts more than sea water;
after this every stroke of the engine will take as much salt out of the boiler by
the pump as is left in the boiler by the steam used in the cylinder for that
stroke. The engine working quick or slow, the quantity withdrawn bears the
same proportion to the quantity left in, and however long the engine may be
worked the water can never be more salt, thus avoiding the evils and incon-
veniencies to which steam vessels have hitherto been subject on long voyages
in being obliged to stop to empty and refill the boiler every fifty or sixty hours
or incur the risk of serious injury to the boiler from the deposition of sal
within them, and a very great sacrifice of fuel the latter part of the fifty o
sixty hours, when the water, from the quantity of salt it contains, is very unfi
for raising steam.
Our Invention, in the second place, consists of returning the heat contained

page_text: in the rejected water again into the boiler, and this we effect by passing the
hot brine and the supply water for the boiler through a system of tubes or
vessels of extended surfaces, called a refrigerator, in the opposite sides, by
which means the heat of the water coming out is communicated to the supply
water going in, the greater part of which is absorbed and returned to the
boiler, thus compensating for the loss of heat that would otherwise be
sustained.
In witness whereof, I, the said Joshua Field, havo hereunto set my hand
and seals, this Eleventh day of April, in the year of our Lord One
thousand eight hundred and twenty-five.