iv. EARTH'S MOTION AND DENSITY, &c. 



413 



Bearing the signature of Const. Huy gens. 



1836d. Small Gregorian Telescope, maker unknown, 

 formerly the property of the late Dowager Viscountess Midleton, 

 date about 1750. Hon. Miss Brodrick. 



1853. Complete Transit of Venus Astronomical Equip- 

 ment, as used by the English expeditions. 



The Astronomer Royal. 



1853a. One of the Telescopes used in the " Transit of 

 Venus" Expedition. 



The French Commission for Observing the Transit of Venus 

 in 1874. 



EYE-PIECES AND OBJECTIVES. 



1837. Objectives and Eye-pieces of the 17th and 18th 

 centuries, the greater part of which were ground and polished by 

 Christian and Constantino Huygens. 



Prof. Dr. P. L. Rijke, Ley den. 



No. 1. Objective of 120 ft. 



No. 2. 84 



No. 3. 85 



No. 4. 43 7 in. 



No. 5. 43 



Nos. 6 & 7, 34 each 



No. 8. 34 Bearing the name of Chr. Huygens. 



No. 9. 34 Bearing the signature of Chr. Huygens. 



No. 10. 10 ft. 8 in. Bearing the name of Chr. Huygens. 



No. 11. Bearing the name of Hartsoeker. 



No. 12. Objective of 32 ft. Bearing the signature of Marcell. 



Nos. la and b. Eye-pieces of 7|- and 8 inch, to use with objective No. 1. 



No. 2a. 6 , 2. 



No. 5a. 4^ , 5. 



No. 7a. 3f , 7. 



No. 8a. 3 , 8. 



No. lOa, 2 ...! " 10 " 



1838. Photograph of the Lens by which Huygens dis- 

 covered Saturn's King. Prof. Buys-Ballot, Utrecht. 



This lens is stated to be the same by which Christian Huygens made 

 out Saturn to be surrounded by a ring. It bears the inscription " X. 3 FEBR. 

 " GODCLV (Eebr. 1655), Admovere oculis distantia sidera nostris." 



1838a. Two large Objective Glasses mounted on brass. 



M. Evrard, Paris. 



1840. Metal for a Newtonian Reflector, with several 

 wooden eyepieces, but without tube or mounting, by Hadley. 



Royal Society. 



IV. APPARATUS FOR DETERMINING THE EARTH'S 

 MOTION AND DENSITY, &c. 



1841. Apparatus used by Bailyin repeating the Ca- 

 vendish Experiment. Royal Astronomical Society. 



