406 Memoranda respecting Experiments to ascertain 



Memoir on a new micrometer and megameter, presented to 

 M. de Sartine, by the Abbe Boscovich. 



A new prismatic micrometer, for measuring small angles, in- 

 vented in 177G by the Rev. Neville i\l;iskelyne. 



A letter to Mr. Maskelync, from the Abbe Rochon, on his 

 prior claim to this discovery. 



A memoir on a new instrument for measuring the sun's sol- 

 sticial altitudes with great precision, and generally all other large 

 angles. 



On the measurement of the dispersion and refraction of dif- 

 ferent substances ; and a description of the instrument which 

 was used in this determination. 



A table of the refraction and dispersion of different substances. 



Description of a machine for engraving; and the report made of 

 it to the Academy of Sciences by ^Iessrs.Condorcet and Bossu. 



An essay on the degrees of warmth of coloured rays (the sub- 

 ject of this memoir). 



Reflections on achromatic telescopes: with eleven plates. 



Some of these papers, for the reason above mentioned, arc 

 probably as little known as the one I have sent you ; scarcely 

 any references to them are to be met with in English works. 

 They all appear to be curious, and deserving the attention of those 

 whose studies or amusements may be directed to subjects on which 

 they treat. As it is always useful to know where information can 

 be obtained at those times, a sketch of them is here given for 

 that purpose. 



If the whole coarse of experiments contained in the Abbe's 

 memoir be collected into one point of view, they will stand as 

 iolluws: 



Talle 



