Improvements in Apparatus for Adjusting the Electric or other Light in Projecting Lanterns.
Year: 1888

page_text: Date of Application, 14th Nov., 1888
Specification Accepted, 31st Dec., 1888
COMPLETE SPECIFICATION.
Improvements in Apparatus for Adjusting the Electric or other
Light in Projecting Lanterns.
1 HERBERT CHARLES NEWTON, Optician, of 3 Fleet Street, London, E.C., do
hereby declare the nature of this invention and in what manner the same is to
he performed, to be particularly described and ascertained in and by the following
statement:
My invention relates to an arrangement for the more convenient working of Electric
or other Lanterns for Projection.
Owing to the difficulty of keeping the light of an electric Arc Lamp accurately in
the optical centre of a Lantern, and to the difficulty experienced, until recently, of
obtaining a sufficiently steady light, particularly for microscopical projection, the Are
Lamp has not been as largely used, as it would undoubtedly have been, otherwise.
Arc Lamps, however, of more than one form, have lately developed such steadiness,
that only some simple and accurate means of centreing and keeping the light centred
in spite of the uneven burning of the carbons, is required, to enable this method of
illumination to be used with far greater success than heretofore.
So-called Focus-keeping Lamps are not nearly accurate enough in their working,
for the purpose, as they only approximately keep the light centred.
To bring the light at first to the optical centre, requires movements in three
directions up and down; to and from the optical system; and from side to side.-
The first of these adjustments has been obtained in various ways;-by raising first
the upper and then the lower carbon; and in pendent lamps, by fitting a screw
motion to raise and lower them.-The first of these methods so disturbs the current as
to put the lamp out for the moment, and is apt afterwards to make it unsteady.-The
second method fails by making it impossible to fit a backwards and forwards, and a
lateral motion, to a pendent lamp, except by means of separate sliding fittings, which
are, however, not nearly delicate enough. This difficulty of adjustment has been so
great, that it has been customary to fit the optical portions of Electric Lanterns in
such a way as to permit of their being moved to and from the light, in preference to
moving the light, which has been the ordinary method of adjustment, in lanterns
fitted with other luminants.

page_text: This method answered fairly well when the powers used were low, and the fronts
small and light; but the weight of the more recent instruments, and the accurate
centreing necessary for the high power objectives now employed, necessitate the
utmost rigidity and any sagging from sliding fittings would be fatal to good results.
Some device, therefore, is needed by means of which the entire lamp may be freely
moved in any one of three different directions, without in any way affecting its
illumination or its position in regard to the other two directions.
In the accompanying drawing, I have shewn apparatus which I have designed for
giving movement to the lamp in the three separate directions required.
Fig. 1 is a plan view.
Fig. 2 a side elevation.
Fig. 3 an end elevation, and
Fig. 4 is a diagram to shew the position of the apparatus within the Lantern.
It will be understood that my invention may be applied to both pendent and standing
lamps, but the accompanying drawings show only the latter application.
A is the lantern box or casing, to the bottom of which is screwed, or otherwise
secured, a base plate or frame B, provided with dovetail guides for a traversing
frame C. This frame carries another C,--which is also provided with dovetail guides,
in which traverses the frame D at right angles to the line of traverse of the
frame C.
The frame is fitted with a horizontal screw c, passing thro', and secured against
endway movement within, its end, and working in a threaded nut & fast on the base
plate framing B.-By the aid of this screw, the frame C is given a to and fro move-
ment in the direction of its guides.-The frame D) is also provided with a screw d,
which lies at right angles to the screw c, and works in a nut fast upon the
frame Collars are provided upon the screw spindle to prevent end way movement
through the end of the frame D, so that the said frame D is traversed backwards and
forwards at right angles to the frame by means of its screw d working in its
nut c¹.
A traverse movement having thus been obtained in two horizontal planes, a vertical
or up and down movement is provided in the following manner :-
Upon the upper face of the frame D is screwed a metal casting E, carrying a pair
of vertical dovetail guides e, in which slides the plate f, which forms part of the
horizontal table F.
This table F is supported upon the vertical screw G, an internally threaded sleeve G'
surrounding the screw G and a hollow pillar G, which latter is screwed to the
traversing frame D.-The sleeve G' fits within the upper part of the pillar G2, and is
held therein by a set screw, but is free to rotate. The screw G, which is the immediate
support of the table F, is secured firmly thereto, so that the rotation of the sleeve G
forces the screw G upward or downward, and with it the table F, which rises and falls,
steadied by the plate and the guides e.
The rotation of the sleeve G¹ is preferably effected by bevil gearing (see Fig. 3
of the drawings), but any other suitable contrivance may be employed.
The spindle for operating this bevil gearing, and also the screws c and d, for
traversing the frames C and D, terminate in milled heads, and are carried out beyond
the lantern casing, so as to obviate the necessity of opening the same to adjust the
position of the table F.
Upon this table stands the electric arc lamp, which may be of any approved
pattern, and is merely indicated in the diagram Fig. 4 by the carbon points.
In fitting a pendent lamp in a lantern, the base plate B would be screwed to the
lantern top, and the position of the whole apparatus reversed.
The apparatus is constructed of gun metal or any other suitable material.
The lamp having been secured to the table F of the regulating contrivance just
described, the light may be moved upward or downward and sideways, so as to bring
it in line with the optic axis of the lenses with the greatest accuracy, while at the
same time its advance to, and retirement from the optical system is provided for.
Thus, the operator is enabled without difficulty to centre his lamp, and re-adjust

page_text: readily the centreing, should it become disturbed by reason of the uneven burning of
the carbons, or other similar cause.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is :-
The application to lanterns of projection, of apparatus consisting of an adjustable
table capable of independent movements in three different planes as hereinbefore
described, by means of which the proper position of the lamp within the lantern may.
be attained and readjusted for the purpose set forth.
Dated this 14th day of November 1888.
NEWTON & SON,
Agents for the Applicant.