AN INSTRUMENT OR INSTRUMENTS FOR ASCERTAINING THE SALTNESS OF WATER IN BOILERS
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
PEDDIE How, of the United States, now residing in Basinghall Street,
Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Eighteenth day of July,
One thousand eight hundred and forty-nine, in the thirteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Andrew Peddie How, my exors, adñiors, and assigns, Her especial licence, full
power, sole privilege and authority, that I, the said Andrew Peddie How, my
exors, admors, and assigns, and such others as I, the said Andrew Peddie How,
my exors, admors, or 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, and in the Islands of
Guernsey, Jersey, Alderney, Sark, and Man, and in all Her said Majesty's
Colonies and Plantations abroad, my Invention of "AN INSTRUMENT OR
INSTRUMENTS FOR ASCERTAINING THE SALTNESS OF WATER IN BOILERS;" in which
said Letters Patent is contained a proviso that I, the said Andrew Peddie
How, should cause a particular description of the nature of my said Inven-
ion, and in what manner the same is to be performed, by an instrument
n writing under my hand and seal, to be inrolled in Her said Majesty's
High Court of Chancery within six calendar months next and immediately
fter the date of the said in part recited Letters Patent, as in and by the
ame, reference being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Andrew Peddie How, do hereby declare that the nature of my said Invention,
and in what manner the same is to be performed, are fully described and
set forth in and by the present Specification thereof, reference being had to
the Drawings hereunto annexed, that is to say :-
My Invention consists of an instrument, which I call a "Salinometer," by
the use of which and by the mere inspection of the indications which it
affords, the exact degree of density and consequently of saltness possessed by
the water in the boilers of marine steam engines can be ascertained at all
times and under all circumstances, independently of the pressure within the
boiler; and the engineer be thereby enabled to determine when the water has
attained to such a degree of saturation as to render freshening necessary
in order to prevent any deposition of salt from taking place.
Figure 1 is a side elevation in section of this instrument; Figure 2, a
transverse sectional view of it; and Figure 8, a plan on the line a, b, of
Figure 1; A is a metallic cylinder, with back piece c, by which it is screwed
on to the front of the boiler B; C, C", are two passages made through the
back piece c, by which a communication is established between the interior
of the cylinder A and two pipes D and E, the former of which leads upwards
towards the top of the water in the boiler, and the latter towards the bottom
of it. F and G are stopcocks attached to the passages C¹ and C"; H
(Figure 2) is a discharge pipe to the cylinder A, and ha stopcock by which
it is opened and closed; J is a waste or overflow pipe fixed within the
cylinder, which reaches at top to within a short distance of the top of the
cylinder A, and terminates at bottom in the discharge pipe H, a little way
below the stopcock h; K is a hydrometer, which floats in the water when
admitted from the boiler into the cylinder at a height corresponding to the
density of the water, and has a graduated stalk which moves up and down
through a guide hole in a bracket n; O is a thermometer, which is also
mounted within the cylinder A to indicate the temperature of the water
therein; M is a cap which in Figure 1 is represented as raised from off the
instrument, in order to shew the other parts more clearly. The mode of using
the instrument is as follows:-When the boilers are in work, one or other of
the passages C', C", is always kept open, but one only at a time. The conse-
quence of this is, that, first, the cylinder A is filled to the height of the mouth
of the overflow pipe J, and that then a continuous inflow takes places from
the boiler on the one hand, and a continuous outflow from the waste pipe on
the other, that is to say, there is a constant flow of water through the salino-
meter of the same density precisely as the water in that part of the boiler

page_text: from which the supply is derived, which density is shewn on the graduated
stalk of the hydrometer. Supposing, therefore, (by way of illustration) the
passage C, which communicates with the top of the boiler, to be that
which has been left open, and that it is desired to ascertain what the density
or saltness of the water is at or near to the bottom of the boiler, the
passage C is closed by the stopcock F, and the other passage C", which
communicates with the bottom of the boiler, opened (by turning the other
stopcock G), when, in an instant or two, the water from the top of the boiler
is entirely displaced by that from the lower part, and any difference which
there may be in their respective densities is indicated by a corresponding rise
or fall of the hydrometer. A thermometer is combined with this instrument,
because the density or saltness of the water varies with the degree of tempe-
rature, and it is necessary to correct the indications of the hydrometer by those.
of the thermometer as often as the hydrometer rises or falls beyond the
standard point to which it may have been graduated. Thus, supposing the
hydrometer to have been graduated on the assumption of the water being at a
uniform temperature of 200° Fahrenheit, and that represents the density
of the water at that temperature, I find from long experience and obser-
vation that for every 10° in the temperature of the water, one eighth of a
degree, or thereabouts, must be deducted from the hydrometer numbers, and
for every 10° of decrease one eighth of a degree, or thereabouts, must be
added. For example, if the temperature is encreased to 210°, a deduction
of must be made on that account from the, which will bring the density
to, or, if the temperature is lowered to 180°, then an addition of must
be made, which will make the corrected density. It must not be supposed
from this, however, that the indications of this instrument are at all affected
by the temperature of the water in the boiler, so far as that temperature
affects the pressure, for, on the contrary, the salinometer is advantageously
distinguished from all other instruments having the same object in view in
this, that it is entirely independent of the boiler pressure. The water when
it comes into the density measuring cylinder A is entirely relieved from the
pressure of the steam in the boiler, and remains subject only to the ordinary
atmospheric pressure. The instrument is represented in the annexed Drawings
as attached to the front of the boiler, but it may be detached from and
removed to any distance from it that may be thought advisable, by simply
lengthening the communicating pipes D and E. Instead, also, of the salino-
meter being made to communicate by two different pipes with the boiler, oue
leading towards the top and the other towards the bottom of the water, one
pipe will suffice in all cases where a rough approximation to the average

page_text: quality of the water in the boiler is all that is required to be ascertained, and
that pipe may be introduced into the boiler at any point which may be most
convenient.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I make no claim to
the application of either the hydrometer or thermometer to ascertaining
the density or saltness of the water of marine steam engine boilers. But
that what I claim as of my Invention is, the peculiar arrangement, com-
bination, and adaptation of means (each by itself well known) embodied in
the single instrument before described, whereby the marine steam engineer
is enabled, by the mere inspection of the said instrument, to ascertain, at
all times and under all circumstances, the density of the water in the boiler,
independently of the pressure within the boiler.
In witness whereof, I, the said Andrew Peddie How, have hereunto
set my hand and seal, this Twenty-fourth day of August, One
thousand eight hundred and fauty nine