How to work with the spectroscope (Google eBook)

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1878
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Page 46 - Under these circumstances the limits of correction for the path of the rays in their passage through the dispersing prisms are very limited and must be strictly observed. The usual method of correcting by the outer surface is inadmissible. For the sake of simplicity, some of the work of the lower part of the micro-spectroscope is omitted in the engraving. As to the method of using this contrivance : With the apparatus just described, measure the position of the principal Fraunhofer's lines in the...
Page 45 - H, the slide which holds the glass plate is made to travel in grooves, and the fine pointer is made to traverse the whole length of the spectrum. It might at first sight appear as if any ordinary spider's web or parallel wire micrometer might be used instead of this contrivance. But on closer attention it will be seen that as the spectrum will not permit of magnification by the use of lenses, the line of such an ordinary micrometer could not be brought to focus and rendered visible. The bright pointer...
Page 14 - ... of the main plate of the spectroscope, which is slotted to allow it to pass through. On moving the central pivot the whole of the prisms are moved, each to a different amount in proportion to its distance in the train from the first or fixed prism, on which the light from the slit falls after passing through the collimator, C. Thus, supposing the first prism of the train...
Page 42 - ... Disappointment will occur in any attempt at delicate investigation, if this direction is not carefully attended to. When the spectra of very small objects are to be viewed, powers of from \ in.
Page 54 - BROWNING'S NEW LARGE AUTOMATIC ELECTRIC LAMP. In this Lamp both carbons are moved by the electricity of the battery employed (without the aid of clockwork) ; the light remains uniform in height, and more steady in action than any of the expensive regulators previously introduced.
Page 62 - PLEA for REFLECTORS: being a Description of the New Astronomical Telescopes, with silvered glass specula, and instructions for using and adjusting them, with many Illustrations and Coloured Frontispiece of Jupiter.
Page 14 - ... telescope is moved through any angle it causes the last prism to turn through double that angle. The rays which issue from the centre of the last prism are thus made to fall perpendicularly upon the centre of the object-glass of the telescope, T, and thus the ray of light travels parallel to the bases of the several prisms, and ultimately along the optical axis of the telescope itself, and thereby the whole field of the object-glass is filled with light. Thus the apparatus is so arranged that...
Page 45 - The lens c which is focussed by turning the milled ring M, produces an image of the bright line in the field of view by reflection...
Page 49 - Instrument may be used for showing any of the leading experiments in Spectrum Analysis ; the Fraunhofer Lines ; the Lines in the Spectra of the Metals, and the Alkaline Earths and Alkalies ; the Spectra of Gases ; and Absorption Bands.
Page 46 - Feb. obscure the fiaint light of the spectra, and entirely prevent the possibility of seeing, let alone measuring, the position of lines or bands in the most refrangible part of the spectrum. To produce good effects with this apparatus the upper surface of the compound prism P must make an angle of exactly 45 with the sides of the tube. Under these circumstances the limits of correction for the path of the rays in their passage through the dispersing prisms are very limited and must be...

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