CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF SUN DIALS DESIGNED TO SHEW MEAN TIME
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
NEWTON, of the Office for Patents, 66, Chancery Lane, in the County of
Middlesex, Civil Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-seventh day of June, in the third year of Her reign,
and in the year of our Lord One thousand eight hundred and thirty-nine, did,
for Herself, Her heirs and successors, give and grant unto me, the said William
Newton, Her especial licence, full power, and privilege and authority, that I,
the said William Newton, my executors, administrators, and assigns, and such
others as I, the said William Newton, my executors, administrators, 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 mentioned, should and lawfully might
make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, and also in all Her Majesty's Colonies and Plantations
abroad, an Invention of "CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF SUN
DIALS DESIGNED TO SHEW MEAN TIME," being a communication from a foreigner
residing abroad;" in which said Letters Patent is contained a proviso,
obliging me, the said William Newton, by an instrument in writing under
my band and seal, particularly to describe and ascertain the nature of the said
Invention, and in what manner the same is to be performed, and to cause
the same to be inrolled in Her Majesty's High Court of Chancery within six

page_text: 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
William Newton, do hereby declare that the nature of the said Invention,
and the manner in which the same is to be performed, are particularly
described and ascertained in and by the following description thereof, reference
being had to the Drawings hereunto annexed, and to the letters and figures
marked thereon (that is to say): :-
These improvements in the construction of sun dials, designed to shew
mean time, consists in certain machinery, on which the plate and gnomon of a
sun dial is to be mounted for the purpose of adjusting the position of the dial
plate according to the varying difference between solar time and mean time,
in order that the dial on being so adjusted may, when the sun shines upon
it, exhibit the real or mean time of the day instead of the solar time. The
accompanying Drawings represent the improved modes of mounting sun
dials.
Figure 1 shews in perspective the most simple construction of the apparatus
as it would appear when complete and in operation. Figure 2 is a geometrical
elevation of the same, taken on one side. The apparatus may be said to
consist of two distinct parts, the one fixed, called the stand, intended to be
made fast to a firm base; the other moveable, called the saddle or easel, which
carries a moveable dial plate. The stand is, in some respects, formed as a
skeleton reading desk, of frames and rails connected together, as shewn
detached in perspective at Figure 3. There are three quadrilateral frames,
made of metal, two of which AD BE, A D C F, being square and of
equal dimensions, are united at right angles in the line A, D, and are
maintained by the third or horizontal frame B, E, C, F, which serves as a
basis for them both. Rails G H, G I, are fixed in the quadrilateral frames
ADBE, A D C F, crossing the middle of each frame, parallel to their
sides; these two rails united at their junction G, are at right angles to one
another. At the bottom of the rail G, I, is a pivot L, and on the prolonged
end of the rail G, H, is fixed another pivot K. The axis of these pivots is
parallel to the rail G, I, and they are intended to receive the two bushes or
arms by which the saddle or easel is suspended. The plane of the two
rails G H, GI, must be placed in the direction of the meridian, the rail G, I,
standing towards the south if the dial is to be adapted to any northern latitude.
Figure 3 is a bird's-eye view of the stand, drawn geometrically; four
screws 1, 1, 1, 1, passed through the ends of the base frame B, E, C, F, are

page_text: for the purpose of accurately adjusting its level upon the pedestal or base on
which it is to stand, and the graduated sector attached to the side of the
frame D, E, (see Fig. 1,) with its plumb line, will afford the means of
accurately determining the level, the pedestal or base being previously con-
structed so as to have a sufficient inclination to compensate the difference
existing between the latitude of the place and the angle of 45 degrees, which
forms the natural inclination of the rail G, I, to the base frame of the stand.
The stand being thus properly set, the rail G, I, will be parallel to the axis of
the earth, the plane of the two rails G H, G I, will be in the plane of the
meridian, and the quadrilateral frame A, D, B, E, will be parallel to the plane
of the equator, and indeed they may be said to represent those imaginary
planes. The saddle or easel, shewn detached in perspective at Figure 4, is
formed of two quadrilateral frames of metal NQ MT, NQRS, of equal
dimensions, united at right angles in the line N, Q, and supported by a metal
rail O, P, fixed to the middle of the sides M, T, and R, S, and forming an
angle of 45 degrees with cach. This rail O, P, carries near each of its
extremities an arm or tenon U, U, with a hole bored through, forming two
bushes or rings for suspending the saddle or easel on the two pivots K and L
of the stand (Fig. 3); the lower bush is the only one of the two which bears
on the boss of its pivot L, the upper bush merely holds up the saddle or easel
by the upper pivot K. The gnomonic graduated plate of the sun dial, shewn
at Fig. 5, is to be fixed on the saddle or easel in a horizontal position by two
screws i, i, so that the edge of the gnomon or style e, t, be exactly parallel
to the rail O, P, or more properly speaking, to the axis of suspension
passing through the two bushes U, U. This condition of perfect parallelism
is essential, without which the dial cannot have the precision and exactness
required in the various positions which it is to assume to indicate accurately
the mean time. In the rail G, H, on the face of the quadrilateral frame A, D,
B, E, (shewn also detached at Fig. 6,) a pivot z is fixed, upon which a metallic
toothed wheel K, K, K; turns freely; this toothed wheel has a graduated
circle on its face divided in 365 parts, equal in number to the days of the
year, and upon this circle are engraved the names of the months, and the
necessary numbers for indicating the days of each month. Only 365 divisions
are made, although there be a 366th day in the leap year, but this extra day
introduced every fourth year, and constituting the 29th of February, amounts
only to about six hours every year, the neglecting of which occasions a very slight
difference between the mean time and the real time, which can never cause an
error of more than a few seconds, quite imperceptible on a dial of ordinary
dimensions. On the middle of the toothed wheel is fixed an eccentric plate or

page_text: cam m, called the governor, the edge of which is curved in such a manner
that, with respect to each division of the circle of days brought under an index
or pointer, the said curve presents for every day a projection or difference
of radius corresponding exactly with the difference between the solar and the
mean time; this plate or governor is also called the curve of the mean time.
The upper pivot K of the rail G, H, forms also a pivot for a bent arm
a, b, c, h, i, j, to swing upon; to this bent arm is connected the upper bush
of the saddle or easel which carries the sun dial (see Fig. 1). The bent
arm forms a lever by which the dial, with its saddle or easel, is occasionally
moved in a vibratory direction for the purpose of placing the dial plate
at a small inclination out of the true horizontal plane. On the side of
the bent arm an adjustable screw bolt g is inserted, which by the action of a
helical spring p is brought against the curved edge of the excéntric plate or
governor, so that as the plate is turned round the bent arm or lever will be
moved in pendulous directions to and fro upon the face of the graduated
wheel K, and consequently by its motions give an undulatory movement to the
dial plate to which it is connected, causing the dial plate to incline from its
horizontal position. Fig. 7 represents, drawn on an enlarged scale, the bent arm
or lever detached, with a portion of the eccentric plate or governor, and also a
part of the toothed wheel and of the lower rail of the rectangular frame B, E;
and Fig. 8 is a side view of Fig. 6 upon the same enlarged scale as Fig. 7.
Upon the rail B, E, a plate Z, Z, is screwed, in which there is a curved
opening x, x; this opening a, a, allows a portion of the circle of graduations
of days and months upon the face of the toothed wheel to be seen; in the
middle of this opening there is attached to the plate a small pointer or index s.
The day of the month for which the dial is to be adjusted must be brought
opposite to this index by turning the wheel round, which may be done by
means of a pinion having a milled head w upon its axle, as shewn at Figures 1
and 8. Upon the plate Z a segmental scale y, y, of graduations is engraved,
which represents minutes of time, the middle graduation marked 60 being the
point of no variation; above and corresponding with this scale a sliding vernier
divided into seconds is placed, which is moveable in a curved slot in the plate;
this vernier is attached to the lower end of the bent arm at i, j, and its middle
line represents mid-day. When the dial has been properly stationed, as above
described, that is, mounted upon its pedestal and adjusted to the latitude of the
place and the true meridian, the observer has to turn the toothed wheel K
until the day of the month in the circle of graduations upon the wheel is
opposite to the index or pointers; this will bring round the cam plate or
governor into such a position as will have caused the Lent arm to advance or

page_text: recede according to the calculated equation of time for that day, which movement
of the bent arm will move the saddle or easel upon its axis L, K, and thereby.
incline the dial plate a little out of its former horizontal position, and hence
(according as the sun may be before or after the true time) the shadow from the
gnomon will fall upon the graduated plate, so much to the right or left of the
line which would give solar time as will indicate the true or mean time on that
day, the scale and venier shewing the difference between the solar and mean
time, that is, the number of minutes and seconds which the time as given by
the sun is before or after the true or mean time. I have hitherto, in describing.
the dial plate as placed horizontally, considered a dial suited to the latitude of
forty-five degrees, which I have done merely as a matter of convenience and
for the purpose of simplifying the description; the place of observation therefore
having greater or less north latitude, the base of the stand must be inclined
accordingly, which will be perfectly well understood by those acquainted with
the science of gnomonies. A small plate spring may be necessary to bear
against the face of the graduated wheel to produce friction and keep it steady.
The dial plate may be placed either horizontally, as described, or vertically, or
two plates, one vertically, the other horizontally, may be adapted to the saddle
or easel, as shewn in Fig. 2, the former directions being carefully attended to.
If instead of a dial of forty-five degrees latitude, which is the most convenient,
it be wished to use another dial for a different latitude, then in order to
accomplish the indispensable condition of of parallelism between the style of
the dial and the axis of suspension of the saddle or easel a universal saddle
or easel must be employed, which, instead of fixed branches as the one above
described, should be provided with moveable branches. The universal saddle
or easel (Fig. 9) may be adapted to every dial, horizontal or vertical, and
consists of three distinct branches united by hinge joints, and shewn expanded
at Fig. 10. The upper part of the frame, on which the dial plate must be fixed,.
has a hinge joint at each angle T, Q; the rail O, P, has its two tenons and
bushes U, U, and a screw m, n, which connects the frame and forms part of
the side; Q, P, may be lengthened or shortened at will for the purpose of
raising or depressing the edge Q of the plate, in order that the saddle or easel.
may be enabled to receive any dial adapted to from thirty to sixty degrees
of latitude. This universal saddle or easel may be applied to higher or
lower latitudes, either by lengthening the uniting screw, or by shortening
it and substituting for the piece or plate o, p, a piece shewn detached at
Figures 11 and 12, which would allow the angle of latitude to be reduced to
nought. The general construction of the mechanism by which I propose to
shift the inclination of the dial plate according to the time of year at which

page_text: the observations is to be made, for the purpose of shewing true time upon a
sun dial, and the mode of adjusting the dial to the latitude of the places of
observation being explained, it will be unnecessary for me to point out all the
modifications which would be required when the dial plate is not set at right
angles to the meridian, as that will be understood by all those who are
acquainted with dialing; and if the dial be adapted for countries lying in south
latitude, it is obvious that the gradation of the wheel and the general
arrangement of the whole must be reversed; this, however, will be well under-
stood. It is therefore only requisite for me to say that the subject matter of
this Invention, and which I claim under the above recited Letters Patent, is a
mechanical arrangement, by which I am enabled to shift the position of a sun
dial, and thereby adjust it for every day in the year, so that the shadow thrown
upon the dial from the gnomon when the sun shines shall indicate, not the
solar time as heretofore, but the mean or true time as given by a well regulated
clock or other timekeeper.
In witness whereof, I, the said William Newton, have hereunto set my
hand and seal, this Twenty-seventh day of December, One thousand
eight hundred and thirty-nine.
Inrolled the Twenty-seventh day of December, One. thousand eight
hundred and thirty-nine.