1#0 Proposed Scientific Meeting at York- 



\y affected by differences in the thickness of glasses, if their 

 state as to colour is the same. 



One other property of the double object-glass remains to 

 be mentioned ; which is, that when the longer aplanatic focus 

 is used, the marginal rays of a pencil not coincident with the 

 axis of the glass are distorted, so that a coma is thrown out- 

 wards ; while the contrary effect of a coma directed towards 

 the centre of the field is produced by the rays from the shorter 

 focus. These peculiarities of the coma seem inseparable at- 

 tendants on the two foci, and are as conspicuous in the achro- 

 matic meniscus, as in the plano-convex object-glass. 

 (To be concluded in next Number.) 



Akt. XXI. — Notice respecting the proposed Scientific Meet- 

 ing at York on Monday the %6th of ' September. 



Some months ago it occurred to the Editor of this work that 

 the general interests of science might be greatly promoted by 

 the establishment of a Society of British Cultivators of Science, 

 which should meet annually in some central town in England. 

 He accordingly corresponded on the subject with several influen- 

 tial individuals, and found that there was a general desire for the 

 organization of such a society. As York possessed peculiar ad- 

 vantages for the first place of meeting, from its local position in 

 reference to the three capitals of the kingdom, — from its having a 

 Philosophical Society, containing many distinguished members, — 

 and from its having a museum and other apartments, suited for 

 the meetings of the society, he addressed himself to Mr Phillips, 

 the Secretary to the Yorkshire Philosophical Society, in order to 

 ascertain how such a meeting would be viewed by that society 

 and by the principal authorities in York. Mr Phillips lost no 

 time in obtaining the desired information ; and having made ap- 

 plication to the Mayor of York, (the Right Honourable Lord 

 Dundas, we believe,) he was able to report that the authorities 

 of York entered heartily into the plan, and that the Philoso- 

 phical Society would willingly charge themselves with any pre- 

 liminary arrangements which might be necessary. 



Upon receiving Mr Phillips's letter, I transmitted it to John 

 Kobison, Esq. who had kindly agreed to act as interim secretary, 



