46 P. J. UYLENBROEK 



3. Additional apparatus, bij D'. Pound, presented by D'. Bradley. 



4. Ditto by M'. Cavendish. 



23. An objectglass by Huygens of 170 feet focal length. Presented to the Royal Society 

 by Sir Isaac Newton, P. R. S. 



24. An objectglass by Huygens , with two eye glasses by Scarlet, for a telescope of 210 feet. 

 Presented by the Rev. Gilbert Burnet M. A. F. R. S. 1724. 



Tres igitur Icntcs objectivas Societas Regia possidct, Ilugenii nomine insigncs, unam 120 fere 

 pedum cum suo oculari ; qua , procul dubio , deinceps Poundius usus est. Hanc lentem 

 Hugenius Socictati dedisse dicitur a°. i6gi. 



Alteram lentem pedum j 70 , etiam Hugcnianam , cidem Socictati donavit summus Newtonus. 



Tertiam denique lentem, omnium maximam , 210 pedum sc. , quam ipsi obtulit Burnetus. 



Quod ad priorem harum lentium attinet, alteri ejus superficiei insculptum est: 



c. HUTOENS , 4 Jun. 1686; 

 allcri 



Ped. 133. 



Alia vero manus addidit hacc verba : vitrum praestantissimum. Wm. Derhara. Tegitur porro 

 charts crassiori , ejusdem magnitudinis , cui hoc inscriptum est : » 4J"ne 1686. This object- 

 glass (w<:^ was wrought by the two brothers M'. Christian and M'. Christopher Huygens) , 

 with the eyeglass accompanying it of 6 inches, makes a telescope of 126 feet , as good I 

 believe as any the world affords. The tackle in the box with it , is the very tackle , the two 

 Huygens managed the glass w"; Wm. Derham. Ped. 122. Royal Society n°. 22. » 



Denique in Diarii Societatis Regiae vol. IX p. 68. sequentia reperiuntur : 



December |§ 1 69 1 . The President ( Sir Robert Southwell K"^. ) in the chair. 



The same (D'. Hooke) produced before the Society a curious object-glass of a telescope, 

 intended to be given them by M'. Hugens. He said it was for a telescope of 120 feet long, 

 to be used without a tube , and its aperture was 8 inches. He forbore to describe the 

 manner of using it , as reserved till M'. Hugens himself should be present. 



Altera lens 170 pedum, quam Newtonus Socictati R. dono dedit, idem nomeu eodem litte- 

 rarum ductu fert sc. » C. Huygens 26 Juny 1686. 



Tertia denique 210 pedum a Bumeto oblata eadem quoque signatura distincta , coufccta 

 est 23 Julii 1686. 



Quoad hanc ultimam, inter annotationes Societatis Regiae Lond. seqq. leguntur. 

 Jan'^y the 7th. 1724 i72f. The President in the chair. 



M'. Hasley of the Temple had leave to be present. 



The reverend M'. Burnett send the Society by the hands of M'. Professor Bradley a present 

 of the glasses belonging to the longest of all M'. Hugens's telescopes, being that of 210 feet. 

 The object-glass of this telescope , with that of another , for 1 70 feet ( since bought bij Sir 

 Isaac Newton) are mentioned by M'. Hugens in his Cosmotheoros , with a particular en- 

 comium, as being not only tlie largest of the kind, but also the most perfect as to tlie 

 exactness of figure of any that had ever yet been contrived , and as such they were pre- 



