1868.] Mr. W. Iluggins on a Hand Spectrum-Telescope. 243 



it is continuous or consists of bright lines. On account of the low mag- 

 nifying-power of the instrument, the red prominence would appear suffi- 

 ciently small to permit of bright lines being distinguished on its spectrum, 

 if such should exist. 



The instrument should be previously focused by the observer on the 

 moon, or some distant object. 



Should a portion of the suri's limb be visible, the instrument must be 

 rotated until the spectrum of tlie little projecting prominence appears in a 

 direction parallel to that of the spectrum of the sun's limb, and is not 

 overlapped by it. Perhaps a diaphragm across the field of view and cut- 

 ting off about one-third of it would be an advantage, as the spectrum of 

 the sun's limb might be concealed behind it. The eye, relieved in this 

 way from the bright solar spectrum, would be in a more favourable state 

 to examine the fainter spectrum of the red prominence. 



Four of these instruments, made by Mr. Browning, have been sent out 

 by the Royal Society to India, to be placed in the hands of observers 

 stationed at different places along the central line of the eclipse. This in- 

 strument would be specially suitable for use at sea. 



Postscript. — Mr. Browning has recently suggested a method of diminish- 

 ing the apparent velocity of meteors by the use of a concave cylindrical 

 lens placed with its axis perpendicular to the direction of their motion. 

 This mode of observing may be applied to the spectrum-telescope by sub- 

 stituting, when required, a plano-convex cylindrical lens for the eye-lens of 

 the eyepiece. If this lens be placed with its axis parallel to the height of 

 the compound prism before the object-glass, and if the telescope be held 

 in a position such that the direction in which the light of the meteor is 

 dispersed is perpendicular to that of its motion, the spectrum of the 

 meteor will be magnified, as when the ordinary eye-lens is employed, but 

 the apparent velocity of the meteor will be less by an amount equal to the 

 magnifying'power of the eye-lens. 



January 30, 1868. 

 Lieut.-General SABINE, President, in the Chair. 

 The following communications were read : — 



I. Remarks upon Archceopteryx lithographica?^ By Prof. T. H. 

 Huxley, LL.D., F.R.S. Received January 1, 1868. 



The unique specimen ArchcBopteryx lithograpJiica (von Meyer) which 

 at present adorns the collection of fossils in the British Museum, is un- 

 doubtedly one of the most interesting relics of the extinct fauna of long- 

 past ages ; and the correct interpretation of the fossil is of proportional 

 importance. Hence I do not hesitate to trouble the Royal Society with 



