9(i On the Varnish and Varnish Trees of India. 



as they are in this instrument, although it is true that any 

 errors, either in colour or spherical aberration, are only those 

 due to a 3-inch aperture, with 6g-inch focus, which, under 

 any circumstances, would not be very great ; and this, again, 

 I must beg leave to observe, is an important advantage, viz. 

 that, with the errors due only to such a telescope, we have 

 constiucted one of double that aperture, viz. 6 inches, and 

 focal length of 1 feet 6 inches. 



The following are amongst the>,most severe tests to which 

 this telescope has been at present submitted. Polaris appears 

 a beautiful picture of a sun and planet. The small star 

 in Aldebaran is so bright as to be seen the instant that the 

 eye is applied to the telescope. The small star in a Lyrse is a 

 little less obvious, but still distinctly visible, s Persei is seen 

 very clearly double, as is also w AurigcB and the double star 

 5 Aquarii is so well-defined, that no question can be entertain- 

 ed as to the inequality in the size of the two stars, although 

 this has been hitherto considered rather doubtful. I hope 

 soon to be able to submit this telescope to more numerous and 

 severe tests. I have omitted to state, that the highest power 

 I have yet used is Jour hundred, — I remain, Dear Sir, your's 

 truly, Peter Barlow. 



Woolwich, November, 19 1827. 



Art. XV. — Notice respecting the Varnish and Varnish 

 Trees of India. 



Having received from George Swinton, Esq. of Calcutta, in 

 India, very considerable quantities of the Indian black varnishes, 

 viz. the varnish of Sylhet, and the varnish from Rangoon in the 

 Burman empire, for the purpose of ascertaining their qualities, 

 and their applicability to the arts of this country, we are desirous 

 of laying before our readers the information respecting these va- 

 luable substances which was sent along with them, and an ac- 

 count of some observations which we have made upon them. 



In the years 1755, 1756, and 1757, a good deal of interest 

 was excited respecting the varnish trees of the East, in conse- 

 quence of a discussion which took place in the Philosophical 



