IMPROVEMENTS IN SPIRIT LEVELS
Year: 1868

page_text: LETTERS PATENT to William Robert Lake, of the "International
Patent Office," No. 8, Southampton Buildings, Chancery Lane,
in the County of Middlesex, Consulting Engineer, for the Inven-
tion of "IMPROVEMENTS IN SPIRIT LEVELS."-A communication from
abroad by Leonard Laroy Davis, of Springfield, Massachusetts,
United States of America.
Sealed the 4th August 1868, and dated the 30th May 1868.
PROVISIONAL SPECIFICATION left by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition,
on the 30th May 1868.
I, WILLIAM ROBERT LAKE, of the "International Patent Office,"
No. 8, Southampton Buildings, Chancery Lane, in the County of
Middlesex, Consulting Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN SPIRIT LEVELS," a communication, to
be as follows:-
My Invention relates to a spirit level with a bubble case capable of
being adjusted to any desired angle, and the nature of the said

page_text: Invention consists in so constructing the level that the bubble glass
when broken may be easily and quickly replaced by another glass;
and also that the bubble glass may be made to correspond with the
base of the level without removing the said glass from its case;
and also that the level may be readily and conveniently adjusted to
ascertain the angle of a surface at any inclination or position. The
frame of the level is made of cast iron or other suitable material, and of
any suitable length. The said frame is preferably constructed with two
parallel straight edges, one of which forms the base of the level; the
said base may have on one edge a scale of inches or other divisions, and
may be provided at one end with an adjusting screw, having on its head
a scale of divisions bearing a certain proportion to the length of the base.
A socket or receptacle is formed about midway between the ends of the
frame, and into this socket a ring which carries the bubble case is
inserted and fitted in such a manner as to turn freely in the same. The
said socket is perforated on each side, and the perforations have screw
threads cut therein to receive screws, formed preferably with conical or
taper points. These screws are fitted into the said threaded perforations
with their points protruding beyond the inner surface of the socket
exactly opposite each other. On the periphery of the ring are placed
studs or projections, which may be secured in place by any convenient
and proper method. These studs are arranged at a distance apart equal
to one-fourth of the circumference of the ring, and are so arranged that
when the ring is in place in its socket they shall be in the same vertical
plane as the conical points of the screws. One of the studs is bevelled
upon that side which is towards one of the screw points and in such
manner that the bevelled surface of the said stud shall be parallel to
the outline of the said point or cone. The other stud is also bevelled
upon the side towards the other screw point, the bevel or inclination
corresponding with the outline of the point or cone. The said studs
are so arranged that when the bubble case is in one position one stud
impinges against the corresponding cone or point, and if the bubble
case or ring is turned one quarter of a revolution in its socket the other
stud impinges against the other cone or point. A screw also having a
conical point is fitted into a hole or perforation in the top of the frame,
the point of such screw protruding beyond the inner surface of the ring.
The point of this screw impinges against a spring having a slight
indentation to receive it. This spring is placed between the said screw
and the ring, the ends of the said spring resting upon the outer surface

page_text: of the ring, and causes more or less pressure to be exerted thereon as
the screw is turned in or out. The socket is provided on its face with
a graduated scale, and a pointer or index is fixed on the side of the
bubble case to indicate upon the scale the angle of the surface upon
which the level is placed. The said pointer is secured to the case by
screws, one of which passes through a slot which allows the pointer to be
adjusted laterally when required.
The level may also be constructed with a socket extending only
half way round the circumference of the ring of the bubble case. In
this modification of my Invention the ring is formed at the outside
portions of its periphery to fit and turn freely in the socket, and the
central portion of its periphery,, which is milled or roughened, affords a
convenient means of adjusting the ring. The bubble case is formed
with apertures at the ends through which the bubble glass is inserted,
the said glass being, preferably secured in its place by calcined gypsum.
Apertures are also formed at the top and sides of the case through which
the bubble can be observed. The base of the level is grooved longi-
tudinally to render it more convenient for levelling shafting. The
adjustment of the bubble glass to make the same true with the base of
the level is effected by means of the conical or pointed screws, cither of
which as it is turned in or out acts upon one of the inclined studs, thus
turning the ring in its socket and raising or depressing the bubble glass
at either end, as desired. By means of the index and scale the angle of
a surface at any inclination may be correctly ascertained, and the
adjustment of the level is facilitated by using the adjusting screw at
the end of the base..
SPECIFICATION in pursuance of the conditions of the Letters Patent,.
filed by the said William Robert Lake in the Great Seal. Patent.
Office on the 30th November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the "International Patent Office," No. 8, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Consulting-
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of May, in the year of

page_text: our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said William Robert Lake, Her special licence
that I, the said William Robert Lake, my executors, administrators,
and assigns, or such others as I, the said William Robert Lake,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and, lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN SPIRIT LEVELS," upon the condition (amongst others)
that I, the said William Robert Lake, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said William Robert Lake, do
hereby declare the nature of the said Invention,, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Sheet of Drawings forming a part of this Specification:-
My Invention relates to a spirit level with a bubble case fitted to turn
in a socket on the base of the level, and capable of adjustment to any
desired angle in relation to the said base.
The nature of the said Invention consists in so constructing the level
that the bubble glass when broken may be casily and quickly replaced
by another glass, also that the bubble glass may be accurately
adjusted to show the true perpendicular and horizontal positions of the
base of the level without removing the said glass from its case, and may
be also readily and conveniently adjusted to any desired angle with
regard to the base to allow the level to be applied to surfaces at any
inclination or angular position..

page_text: Figure 4 is a longitudinal section through the socket and ring; Figure 5
illustrates a modified form of the said level; Figure 6 is a detached
portion of the same. Like letters indicate the same parts throughout
the Drawing.
The frame a of the level is made of cast iron or other suitable material,
and of any convenient length. The said frame is preferably constructed,
as shown in Figure 1, with two parallel straight bars or edges b, b¹, one
of which 6 forms the base of the level. The said bars are united by the
intermediate web 6, which consisting of an openwork ornamental design
is at the same time light and strong, and gives to the level a neat and
finished appearance. The frame shown in Figure 5, which has only one
straight edge, is also very convenient for ordinary levelling purposes.
The base may have on one edge a scale of inches or other divisions,
and may be provided at one end with an adjusting screw, having on its
head a scale of divisions bearing a certain proportion to the length of the
base. A socket or receptacle c, Figures 1, 3, and 4, is formed midway
between the ends of the frame, and into this socket a ring d, which
carries the bubble case e, is inserted and fitted in such a manner as to
turn freely in the socket. The central portion d' of the ring d projects
above the sides d³, ds, and is fitted to turn freely in the recess formed
between the projection c² of the socket and the loose piece c³, which is
secured by the screws for otherwise upon the front of the said socket.
The ring c of the socket is perforated at con each side, and the
perforations have screw threads cut therein to receive screws g, h,
formed preferably with conical or taper points g', . These screws are
fitted into the threaded perforations c³, with their points protruding
beyond the inner surface of the interior of the socket exactly opposito
each other. On the periphery of the ring d are placed studs or pro-
jections i, j, which may be secured by any convenient method. These
studs, as shown in Figure 4, are fixed at a distance apart equal to one-
fourth of the circumference of the ring d, and are so arranged that when
the said ring is properly placed in the socket the studs i, j, shall be in
the same vertical plane as the conical points g¹, h¹; of the screws g, h.
The stud i is bevelled upon that side which is towards the screw g,
and in such manner that the bevelled surface of the said stud shall be
parallel to the outline of the point or cone g' of the said screw. The
other stud j is bevelled upon the side towards the other screw point
or cone, its bevel or inclination corresponding with the outline of tho
said point or cone. The said studs are so arranged that when the bubble

page_text: case is parallel with the base or in a horizontal position, as seen in
Figure 1, the stud i is in contact with the cone or point g'; and if the
bubble case or ring is turned one quarter of a revolution in its socket to
make the bubble glass perpendicular to the base b, as shown in dotted
lines in the same Figure, the other stud j impinges against the other cone
or point . A screw k, also having a conical point, is fitted into a hole
or perforation in the top of the frame, the point k¹ of such screw pro-
truding beyond the inner surface of the ring. The point k¹ of this screw
impinges against a spring having a slight indentation to receive the
said point. This spring, as shown in Figures 3 and 4, is placed between
the screw and the ring d, the ends of the said spring resting upon the
outer surface of the ring d and causing more or less pressure to be
exerted thereon as the said screw is turned in or out. The socket c is
provided with a graduated scale n, which is preferably formed on the
loose piece c³, and a pointer or index o is fixed on the side of the bubble
case e to indicate upon the scale the angle of the surface upon which the
level is placed. The said pointer is secured to the case by screws p, q-
The screw p passes through a slot, which allows the pointer to be
adjusted laterally when required. When it is thus properly adjusted the
screw p is tightened and prevents any derangement or shifting of the
pointer. If desired, the studs i, j, may be square instead of bevelled.
In the modification of my Invention illustrated in Figure 5 I have
shown the socket or ring seat extending only partially around the ring d
of the bubble case. The said ring is in this instrument formed at the
outside portions of its periphery to fit and turn freely in the socket
and is secured by the loose piece c³, as already described. The central
portion d¹ of the periphery of the ring is milled or roughened, as shown
in Figure 6, to afford a convenient means for turning the ring in the
socket. The adjustment of the ring and bubble case in its perpendicular
and horizontal positions is effected by means of the screws g, h, as in
the instrument shown in Figure 1. The bubble case e is formed with
apertures e at the ends, through which the bubble glass 8 is inserted,
the said glass being preferably secured in its place by calcined gypsum,
in which it is embedded, as shown in Figures 3 and 4. Apertures e
are also formed at the top and sides of the case through which the
bubble can be observed. The base 6 of the level may be grooved
longitudinally to render it more convenient for leveling shafting and
other like objects, the adjustment of the bubble glass to make the
same true with the base of the level being effected by means of the

page_text: conical or pointed screws g, h. The level may be used for any purpose
for which ordinary levels and plumb lines have hitherto been employed.
The chief advantages of this level over such ordinary devices lie in its
simplicity and accuracy, and in the protection afforded to the bubble
glass. The true horizontal and perpendicular positions of the level are
given by the adjusting screws, while by means of the index and scale
the angle of a surface at any inclination may be correctly ascertained.
Having thus fully described the said Invention as communicated to
me by my foreign correspondent, and shown what I consider to be the
most advantageous method of constructing and using the same, I
claim,―
First. The bubble case e, with apertures for receiving the bubble glass
and exhibiting the bubble, constructed substantially as set forth.
Second. The ring d, constructed, fitted in the socket c, and secured
by the loose piece c³, substantially as and for the purposes set forth.
Third. The adjustable set screws g, h, fitted through the socket c,
and arranged to act in combination with the studs i, j, on the ring d,
substantially as and for the purpose set forth.
Fourth. The frame a, socket c, (with screws g, h,) adjustable ring d,
(carrying the case e and studs i, j,) the screw k, pointer o, and
scale n, constructed, combined, and operating together substantially as
and for the purposes set forth.
In witness whereof, I, the said William Robert Lake, have hereunto
set my hand and scal, this Twenty-eighth day of November, in
the year of our Lord One thousand eight hundred and sixty-
eight.
WILLIAM ROBERT LAKE. (L.S.)
Witness,
THO. N. PALMER,
Clerk to Messrs. Haseltine, Lake, & Co.,
8, Southampton Buildings,
W.C.