Identifier: pictorialhandboo00weal (find matches)
Title: The Pictorial handbook of London : comprising its antiquities, architecture, arts, manufacture, trade, social, literary, and scientific institutions, exhibitions, and galleries of art : together with some account of the principal suburbs and most attractive localities ; illustrated with two hundred and five engravings on wood, by Branston, Jewitt, and others and a new and complete map, engraved by Lowry
Year: 1854 (1850s)
Authors: Weale, John, 1791-1862
Subjects:
Publisher: London : Henry G. Bohn
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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n diameter, is contained in an iron case,marked zzz in the plate. The polar and meridian adjustments are made bymeans of screws at the lower extremity, rr is the hour-circle, read off by two * The object-glass of this telescope was presented by Sir James South to the University ofOxford, and was by that body transferred to the Radcliffe trustees. f This name is not sufficiently descriptive of the nature and present employment of the in-strument. Various names have been suggested at different periods of its history. The elderDollond called it the divided object-glass micrometer, which is also not satisfactory. M. deCharnieres, a French naval officer of the last century, who has some claims to be regarded asthe inventor of the instrument, called it megameter in opposition to micrometer, which is,perhaps, the least objectionable name that has been proposed, l For the description we are indebted to the kindness of Manuel Johnson, Esq., the directorof the Radcliffe Observatory. 678 LONDON,
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THE HELIOMETER OF THE RADCLIFFE OBSERVATORY. microscopes, one of which, s, is shown in the plate, l l is the declination-circlelikewise read off by two microscopes, one at m, and the other 180° distant fromit. The cylindrical piece, projecting beyond the declination-circle, serves as THE RADCLIFFE OBSERVATORY, OXFORD. 679 a counterpoise to the telescope. The handles which are seen on this cylindri-cal piece are for the purpose of moving the instrument, and, by means ofthem, the observer is enabled to set it in declination very conveniently. The declination-axis is contained in the iron case ggg; it is made of steel,4 in. in diameter, being of the same size as the polar axis, p is one of thecounterpoises of the declination-axis, and there is a corresponding counterpoiseon the other side, the top of which is just seen in the plate. To these coun-terpoises the friction wheels ww are attached, which diminish the pressure ofthe declination-axis on its Ys. pp are counterpoises for the pola

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