IMPROVEMENTS IN THE CONSTRUCTION OF COMPENSATION BALANCES OF CHRONOMETERS
Year: 1843

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN RICHARD
LUND, of Cornhill, in the City of London, Chronometer Maker, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-fifth day of November, in the seventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
John Richard Lund, Her especial licence, full power, sole privilege and
authority, that I, the said John Richard Lund, my exors, adiñiors, and
assigns, or such others as I, the said John Richard Lund, my exors, adñiors,
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, my Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF COMPENSATION BALANCES OF CHRONOMETERS;" in which said
Letters Patent is contained a proviso, that I, the said John Richard Lund,
shall cause a particular description of the nature of my said Invention, and
in what manner the same is to be performed, to be inrolled in Her said
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.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Richard Lund, do hereby declare that the object and nature of my said
Invention, and the manner in which the same is to be used, are described and
represented in the manner following (that is to say) :-
The object of my said Invention is to remove a defect in the construction of
the compensation balance generally used in chronometers (see Figure X, which
is a magnified Drawing of such a balance), from which it is found that when
such a balance is adjusted to mean time for the mean temperatures, about 55°
Fahrenheit, it will fail to correct the effects produced by changes of tempera-
ture upon the balance spring at, towards, or beyond the extreme temperatures,
about 30 or 80° Fahrenheit. From the nature of my Invention no alteration
is required in the form of the compensation balance now generally used, as a
pair of either of the compensation weights I am now about to describe are to
be applied instead of the compensation weights in ordinary use. To facilitate
this description, I shall designate the one as compensation weight Y and the
other as compensation weight Z. The compensation weight Y is shewn in the
annexed Drawings at Figures 1, which, together with Figures 2, 3, 4, 5, 6, and
7, are magnified Drawings thereof and of its several parts. The compensation
weight Z, and its several parts or portions, are shewn at Figures 8, 9, 10, 11,
and 12. In Figure 1, a is a portion of an arc of an ordinary compensation
balance blade, and the remainder of the Figure one of my compensation
weights; Figure 2 is the under side; and Figure 3, a section of Figure 1.
Figures 4, 5, 6, and 7 represent the parts of this weight taken to pieces.
may be called the platform, attached to the balance blade by the screw b¹, as
in the ordinary compensation weights, and as shewn at Figures 2 and 3; c is a
ring to be sprung on to the edge of the platform b, having an upright piece of
metal crising from it, to which is screwed a similar piece of metal c². These
two pieces c¹, c³, may together be called the holder, and it is so constructed as
to carry a circular lamina of brass and steel, or other suitable metals d, and to
be moveable round the platform 6. One end of the lamina may be passed
through this holder, either to the right or left, and then secured by the screws
³, c, c. At the other end of this circular lamina d is fastened by the screw d'
a piece of hardened steel e, or a piece of steel holding a ruby, the steel or ruby
having a hole in it, the edges of which hole are carefully rounded off on either
side. fis what I call the "correcting weight," shewn separately at Figure 7 ;
is a screw screwed into the platform b, having its end formed into a pivot, as
seen in Figure 7, upon which the correcting weight fis made to turn easily,
but steadily and firmly. The end f¹ of the correcting weight furthest from
the screw or pivot g is made of gold or other suitable metal, and attached to the

page_text: remainder of the correcting weight by a screw, as shown. A pin is inserted
at the point h, and a spring i fixed on the platform 6 bears against this pin
with sufficient force to prevent any oscillation of the correcting weight f during
the vibration of the balance. To divide the resistance hereby occasioned to
the action of the laminæ, this spring is placed on the right-hand side of the
correcting weight in the one compensation weight, and on the left-hand side in
the other. In the compensation weight Z, shewn in the annexed Drawings,
Figures 8 & 9, the platform b, the ring c to. be sprung thereon, and the
holders of the laminæ are similar to those used in the compensation weight Y,
already described. The parts of compensation weight Z, which differ from
those of the compensation weight Y, are fully shewn in Figures 9, 10, 11, and
12. At the end of the circular laminæ d, furthest from the holder, there is
a ruby j fixed, which, when the laminæ is influenced by change of temperature,
moves between the two screws k³, k¹, in the piece of brass or lever k, of which
Figure 10 is a face and edge view. ², ³, are two screws at the other end of
the piece of brass or lever k, inserted in the direction shewn in Figure 10.
This lever k turns upon a pivot 7. m is the "correcting weight," and it is
made to slide towards and from the centre of the balance on the pin n, which
is screwed into an upright piece of brass 62, attached to the platform 6; 0, 0,
are screws, the ends of which are used to regulate the freedom between the:
correcting weight and the platform; 1, 1, are pieces of ruby of the form
shewn in Figure 12, which are fixed in the " adjusting arms" p, p, by.
a brass wedge 2, as shewn in Figure 12, where 1 and 2 are respectively.
the ruby and the wedge. Figure 11 is a sectional and face view of the " cor->
recting weight," and Figure 12 are similar views of one of the adjusting arms.
The parts marked q, q, of the adjusting arms, move stiffly in the correcting.
weight, and the ends of the parts q, q, are burnished over in the countersinks on
the under side of it. is a spring fixed upon the platform 6 by the screw r², so
as to keep the rubies 1, 1, in contact with the end of the screws ², k².
My compensation weights are to be treated precisely as_
those in ordinary
use to obtain the adjustment of the balance for the mean temperatures, about
55° Fahrenheit, care being taken during this adjustment, and when compensation
weight Y is to be used, to place, by turning the laminæ round upon the platform;
a diameter of the circular hole in the correcting weight, marked s, Figures 1
and 7, coincident with or immediately over a line t, marked on the platform b,
which if produced would pass through the centre of the balance; and when
compensation weight Z is to be used, like care must be taken to place a dia-
meter of the circular hole in the lever k, marked 's, immediately over a similar
line marked on its correcting weight m, by turning one of the screws k², k³,

page_text: inwards or outwards; at the same time the screws k¹, k', should be turned out-
wards far enough to withdraw their points from the space at the end of the lever
k between the points x, x, and the ruby at the extremity of the laminæ placed
in the middle of this space by turning the lamina round upon the platform;
the sides of the adjusting arms, marked 3, 3, Figure 8, should then be placed
in lines at right angles with the line t, drawn on the correcting weight m, and
the surfaces of the rubies 1, 1, which form the inclined planes, at angles of
about 75° with the sides 3, 3.
Now it will be evident to those who are acquainted with the action of an
ordinary compensation balance that a change of temperature will alter the
position of the "correcting weights" in both the compensation weights Y and Z
by acting on their respective laminæ, as one end of the laminæ in the com-
pensation weight Y is attached to a "correcting weight" by the screw u, and
in compensation weight z the laminæ is made to act on the shortest end of the
lever k, and so change the position of the correcting weight by sliding the
points of the screws ², k, up and down the inclined planes made on the rubies
1, 1; therefore in the compensation weight Y the end of the correcting
weight f, made of gold, will be carried as the temperature approaches 30°
and 80° Fahrenheit, nearer to the centre of the balance, and will become more
and more effective at each variation of the temperature towards these extremes,
thereby counteracting the gradual accumulation of error in the rate of the
chronometer towards the extreme temperatures; and for this reason, that the
end of this correcting weight describes the arc of a circle whose centre g is
distant from the centre of the balance by nearly the whole radius of the balance.
For the same reason the longest end of the lever k of the compensation weight
Z is similarly effective.
The effectiveness of the "correcting weights" in the compensation weights
Y and Z, respectively, is also very much increased by the great difference in
the distance of the ends of the correcting weight from the pivot g in the one,
and by the difference in the distance of the ends of the lever k from the pivot l
in the other; the smallest motion at u, Figure 1, 3, and 7, or at x, x, Figure 8,
becomes considerable at the other end of the correcting weight or lever. These
results I consider to be the most important and valuable effects of my
compensation weights.
My Invention is to be used thus:-The balance of a chronometer is first to
be adjusted for the mean temperatures, as already described, and the error
equally divided at the extremes; then if, as the temperature changes towards
30° or 80° Fahrenheit, the divided error be fast of the rate at 55° Fahrenheit,
and the compensation weights Y are to be used, their laminæ are to be

page_text: shortened by passing them through the holders. If slow of the rate at 55°
Fahrenheit, they are to be lengthened by drawing them out of the holders.
After each adjustment of the compensation weights Y a diameter of each of
the circular holes S in the correcting weights respectively must be made to
coincide with the lines drawn on each of the platforms by moving the rings
round upon them, as already explained. But, if the compensation weights Z
are to be used, the directions are as follows:-The balance is first to be
adjusted for the mean temperatures, as already described, and then the
screws k¹, ki, in each of the compensation weights Z turned inwards, so that
the commencement of the said error and its correction may be simultaneous,
this error being first equally divided at the extremes, as directed above; then,
if the said error is not sufficiently corrected at the extremes, turn the adjusting
arms in each compensation weight Z from the centre of the balance until the
correction of the said error is effected. Supposing the effect thereby produced
to be more than required, turn them towards the centre of the balance. After
each of these adjustments, a diameter of each of the circular holes S in each
lever respectively must be made to coincide with the lines drawn on the
corresponding correcting weight by turning one of the screws ³, k, in each
compensation weight Z inwards or outwards, as the readjustment may require.
If the correcting weights be found too heavy or too light, take up their lamina
through the holders, or draw them out therefrom, as the case may require.
By this alteration the effect of the correcting weights will be modified. The
rubies at the extremities of the laminæ must be replaced after this correction
in a position midway between the parts of each lever K marked x, x, in
Figure 8, by turning the lamina round upon their respective platforms until a
diameter of the holes s in each lever is replaced over a line on the correcting
weight respectively. It is observable that in effecting any of these adjust-
ments or connections in either of the compensation weights Y or Z, for the
extreme temperatures, the position of the compensation weights themselves
are not altered. When the correction of the said error in the extreme tem-
peratures is not required to be very minute or exact one of the compensation
weights Z will be sufficient, and the compensation weight on the other blade
of the balance may be one of those now in use. On the other hand, if very
great exactness be required, use one of the compensation weights Z to about
30° or 90° Fahrenheit, and then resort to the other compensation weight Z to
complete the correction below or above those temperatures. To guard against
accidents, a thin circular metal plate of the same diameter as the compensation
weights Y or Z may be fixed over them by screws in their respective holders.
I do not claim as my Invention any part whatever of the ordinary com-

page_text: pesation balance, nor do I confine myself to the details shewn and described as
long as the peculiar character of my improvements be maintained; but I claim
as my Invention, and as my "Improvements in Compensation Balances
of Chronometers," the mode of constructing the compensation weights of chro-
nometers, whereby they are so provided with lamina that the expansion
or contraction thereof shall, by acting on a part of the compensation weights,
vary the effect of such weights on the compensation balance to which they are
applied.
In witness whereof, I, the said John Richard Lund, have hereunto set
my hand and seal, this First day of May, in the year of our Lord One
thousand eight hundred and forty-four.