DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.1311#0285
OF THE WORLD'S INDUSTRY. 243
CHAPTER XXXIII.
TELESCOPES, ORRERIES, GLOBES, AND MODEL MAPPING.—From the Juries7 Report.
TELESCOPES----YABLEY AND SON—BOSS—CALLAGHAN, ETC.—BURON—KINZELEACH—0BBEE1ES—
FACET----PLANT—PLANETARIUMS----NEWTON AND SON—LE FEHVEE, BRAKE, ETC.—BICHABD's
GEOGRAPHICAL INSTRUCTOR—DETOUCHE AND HOUDIN's UEANOGRAPHIC APPAEATUS—GLOBES
----JOHNSTON—NEWTON AND SON----FLETCHER, EEDKOTJSB, ADOENO, ETC.----MODEL MAPPING----
SCHOELL—IBBETSON, ETC.
The telescope is an instrument of such high importance, that it ought to command at
all times, from opticians, the incessant direction of their attention to its improvement,
and the bringing it to the highest possible state of perfection. In the Exhibition, if we
except those affixed to astronomical instruments, there were but few telescopes. Of those
the larger were for the most part good. Wray exhibited one with discs of a solid
substance, instead of Hint glass, which deserved commendation, as a deviation from
the beaten path, that may conduce to new and important results. There were few
samples in the Exhibition of optical glass; but all were good, and gave great promise
of an increase in the use of large telescopes. Simms exhibited several object-glasses
made of English glass; and Chance contributed a noble piece of apparently pure flint
glass, of no less than twenty-nine inches in diameter. Daquet sent some wonderfully
pure glass, both crown and flint. Of lenses and prisms, there was not one British
contributor; Erance stood alone in the exhibition of some very beautiful work, which
reflected high credit upon Bayerle and Bertaud. Of physical optics, there was but
one extensive exhibitor, viz., Duboscq Soleil, France, who had a beautiful collection of
most delicately constructed instruments, adapted for physical investigation. Of
microscopes there were a good many exhibited ; among which the English microscopes
were found to stand pre-eminent.
Telescopes.—Varley and Son exhibited an apparatus to be used in Gregorian telescopes,
consisting of three small speculums, grouped together on one stem, and fitted into a
telescope, under adjustment from the eye-end, by means of which any one of the three
might be used at pleasure, so that the power may be changed without losing sight of
the object. Within the tube were placed two slides, one near the eye-end, adjustable
by a screw; the other near the object-end, which might be moved to and fro. The
latter carried three small speculums, of different foci, mounted on a steel axis, held
in a stiff frame. At the bottom of the axis was placed a toothed wheel and rack-
work. This rack was kept from moving by a long bar proceeding from the first slide,
so that it could not move with the slide on which it laid; by this arrangement, on
moving the slide, the wheel upon it rolled against the rack, and so presented the next
speculum. The angles at which the speculums are opposed to each other on the block
determines the number of teet>\ or portions of the circle required to present each
speculum. The diameter of the wheel determines the distance that such portion of the
wheel must traverse to put each speculum in true focus. The slide nearest to the eye-
end is moved by a long bar, attached to it by means of a screw, whilst its near end lies
on the other slide, and over the loop-hole. The bar has a screw handle on the outside
of the telescope, by which to pull or push the further slide, and also to clamp it fast to
the near side when in the right place. This clamping connects the two slides, and causes
both to obey the adjusting screw. In order to determine the exact places at which to
clamp, the bar is furnished with three notches, whose distance corresponds with the
CHAPTER XXXIII.
TELESCOPES, ORRERIES, GLOBES, AND MODEL MAPPING.—From the Juries7 Report.
TELESCOPES----YABLEY AND SON—BOSS—CALLAGHAN, ETC.—BURON—KINZELEACH—0BBEE1ES—
FACET----PLANT—PLANETARIUMS----NEWTON AND SON—LE FEHVEE, BRAKE, ETC.—BICHABD's
GEOGRAPHICAL INSTRUCTOR—DETOUCHE AND HOUDIN's UEANOGRAPHIC APPAEATUS—GLOBES
----JOHNSTON—NEWTON AND SON----FLETCHER, EEDKOTJSB, ADOENO, ETC.----MODEL MAPPING----
SCHOELL—IBBETSON, ETC.
The telescope is an instrument of such high importance, that it ought to command at
all times, from opticians, the incessant direction of their attention to its improvement,
and the bringing it to the highest possible state of perfection. In the Exhibition, if we
except those affixed to astronomical instruments, there were but few telescopes. Of those
the larger were for the most part good. Wray exhibited one with discs of a solid
substance, instead of Hint glass, which deserved commendation, as a deviation from
the beaten path, that may conduce to new and important results. There were few
samples in the Exhibition of optical glass; but all were good, and gave great promise
of an increase in the use of large telescopes. Simms exhibited several object-glasses
made of English glass; and Chance contributed a noble piece of apparently pure flint
glass, of no less than twenty-nine inches in diameter. Daquet sent some wonderfully
pure glass, both crown and flint. Of lenses and prisms, there was not one British
contributor; Erance stood alone in the exhibition of some very beautiful work, which
reflected high credit upon Bayerle and Bertaud. Of physical optics, there was but
one extensive exhibitor, viz., Duboscq Soleil, France, who had a beautiful collection of
most delicately constructed instruments, adapted for physical investigation. Of
microscopes there were a good many exhibited ; among which the English microscopes
were found to stand pre-eminent.
Telescopes.—Varley and Son exhibited an apparatus to be used in Gregorian telescopes,
consisting of three small speculums, grouped together on one stem, and fitted into a
telescope, under adjustment from the eye-end, by means of which any one of the three
might be used at pleasure, so that the power may be changed without losing sight of
the object. Within the tube were placed two slides, one near the eye-end, adjustable
by a screw; the other near the object-end, which might be moved to and fro. The
latter carried three small speculums, of different foci, mounted on a steel axis, held
in a stiff frame. At the bottom of the axis was placed a toothed wheel and rack-
work. This rack was kept from moving by a long bar proceeding from the first slide,
so that it could not move with the slide on which it laid; by this arrangement, on
moving the slide, the wheel upon it rolled against the rack, and so presented the next
speculum. The angles at which the speculums are opposed to each other on the block
determines the number of teet>\ or portions of the circle required to present each
speculum. The diameter of the wheel determines the distance that such portion of the
wheel must traverse to put each speculum in true focus. The slide nearest to the eye-
end is moved by a long bar, attached to it by means of a screw, whilst its near end lies
on the other slide, and over the loop-hole. The bar has a screw handle on the outside
of the telescope, by which to pull or push the further slide, and also to clamp it fast to
the near side when in the right place. This clamping connects the two slides, and causes
both to obey the adjusting screw. In order to determine the exact places at which to
clamp, the bar is furnished with three notches, whose distance corresponds with the