# How to use *Spectroscopes* in a sentence

Angular prism

**spectroscopes**are the commonest.In grating

**spectroscopes**both plane and concave gratings are employed in connexion with a collimator and observing telescope.Rutherfurd devised one made of flint glass with two crown glass compensating prisms; whilst Thallon employed a hollow prism containing carbon bisulphide also compensated by flint glass prisms. In direct vision

**spectroscopes**the refracting prisms and slit are in the observing telescope.We readily find (with substitution for k of 27r/X) a2b S n J s in fl „2a2E2 „2b2n2 f2X2 f2X2 as representing the distribution of light in the image of a mathematical point when the aperture is rectangular, as is often the case in

**spectroscopes**.The instruments which effect such a resolution are called

**spectroscopes**.AdvertisementBut the

**spectroscopes**that can be employed for stellar spectroP graphs are not sufficiently powerful to separate fully lines which are very closely adjacent, and therefore a line, assumed to be of a known wave-length, may be apparently displaced by the near neighbourhood of an unknown line.The formula expressing the optical power of prismatic

**spectroscopes**may readily be investigated upon the principles of the wave theory.If, as in common flint-glass

**spectroscopes**, there is only one dispersing substance, f Sy ds = Sµ.s, where s is simply the thickness traversed by the ray.It follows that for observations in which light is a consideration

**spectroscopes**should be used which give about twice the resolving power of that actually required; we may then use a slit having a width of nearly eight times that of the normal one.This analogy is useful because the application of Fourier's analysis to the optical theory of

**spectroscopes**has been doubted, and it may be urged in answer to the objections raised that the instrument acts in all respects like a mechanical analyser,' the applicability of which has never been called into question.AdvertisementThe bands often appear in groups, and such spectra containing groups of bands when viewed through small

**spectroscopes**sometimes give the appearance of the flutings of columns.