HERSCHRL ON COLOURED RINCS. \J~ 



from bearing brandies, the young trees afford blossoms in 



the succeeding year : and I am much inclined to think, from 



experiments I have made on this tree, that by selecting those 



varieties which ripen their fruit early in the autumn, and by 



propagating with grafts or buds from young and vigorous 



trees of that kind, which have just attained the age necessary 



to enable them to bear fruit, it might be cultivated with 



much advantage in this country, both for its fruit and Valuable both 

 ~ , ' tor us trim ana 



timber. timber. 



I have tried similar experiments on many other species of Tried on many- 

 trees, and always with the same result; and I entertain no other trees, 

 doubt, that the effects of time might be thus anticipated in mat urity anti- 

 the culture of any fruit, which is not produced till the seed- cipated, 

 ling trees acquire a considerable age. For I am thoroughly 

 confident, from very extensive* and long experience, that the 

 graft derives nutriment only, and not growth, from the young 

 stock in which it is inserted ; and that with the life of the pa- 

 rent stock the graft retains its habits and its constitution. 



Experiments for investigating the Cause of the coloured con- 

 centric Rmgs, discovered by Sir Isaac Newton, between 

 two Object-glasses laid upon one another. By William 

 Herschel, L.L.D. F.R.S. 



( Concluded from p. W&.) 



XIX. Of the Place where the different Sets of Rings are to 

 be seen. 



JD>Y an application of the same course of the rays, we may pj acc w i iere 

 now also determine the situation of the place, where the dif- the different 

 ferent sets of rings are seen : for, according to what has been are seen.' & * 

 said in the foregoing article, the situation of the primary set 

 should be between the lens and the surface of the looking- . f 



glass : and the place of the secondary on« at the metalline 

 coating of the lowest surface. To try whether this be ac- 

 tually as represented, let us substitute a metalline mirror 

 Vol. XIX.— March, 1809. N with 



