Visit to Mount Etna — Age of a Chestnut Tree. 357 



are facets within the range of the objective. The same 

 result may be produced by placing the microscope in an 

 horizontal position, with the picture, etc., in their relative 

 places, supporting the photograph on a temporary stand; 

 but a slight difficulty occurs, in accurately centering the 

 light, the bull's-eye, and the picture, so as to be in exact 

 coincidence with the axis of the achromatic condenser. This may 

 be got over by enclosing the whole by a tube temporarily fixed 

 to the lower bar of the instrument, as shown in the diagram. 

 By this plan, the whole may be at any time adjusted in a few 

 minutes with the greatest ease and cer- 

 tainty. Fig. 2 represents a portion of the 

 view as obtained by the above means. 

 The uniformity of the portraits show 

 these minute lenses to be of most aston- 

 ishing accuracy and equality of form. 

 And our admiration is excited at their 

 delicacy of construction when we recol- 

 lect that the picture is reduced by this 

 minute marvel of design from one inch 

 to the y^o of an inch in diameter, or, 

 in other words, it is reduced in size 

 2100 times, occupying a surface so 

 small as to require 490,000 to cover one square inch. 



VISIT TO MOUNT ETNA— AGE OF A CHESTNUT 



TREE. 



BY CAPT. E. SMITH, LATE H.M. 44TH KEGIMENT. 



In June, 1811, being employed on the Quartermaster- General's 

 staff in Sicily, and engaged in making surveys of various 

 localities, I visited Mount Etna, and of course did not neglect 

 to examine that vegetable wonder, the Castagno di cento 

 Cavalli, which seemed to me, as it had done to other travellers, 

 not what was expected — a single tree, but apparently a cluster 

 of five distinct trees, since reduced, I understand, to three. 

 A late traveller has remarked, and I think with good reason, 

 that a large tree may have existed on the spot, and that on 

 its destruction in some of the many convulsions that have so 

 often shook Etna to its very centre, the present cluster of trees 

 sprang from its root. 



But it is not of the Castagno di cento Cavalli that I am 

 about to speak, it is of a more wonderful production of nature 



