14 



On the Different Methods of Measuring 

 Microscopical Objects. 



Memoir by Count A. F. Castracane cV Antelminelli. 

 (Read November 26th, 1869. J 



It is not only to those who contemplate the immensity of the celes- 

 tial bodies, or the wonderful harmony of the stars, and of their 

 movements, that it is given to feel themselves transported with 

 amazement when reflecting on the infinite wisdom of the Creator. 

 The earth and the sea, under whatever aspect they are regarded, 

 and even in most minute details, give evident proof that all proceeds 

 from the same infinite, ordaining Mind. Or rather, all that pro- 

 ceeds from the hands of the highest Artificer cannot but be equally 

 stupendous in itself, so that man feels himself compelled to marvel 

 more when he reflects on the organization of the most humble 

 flower of the field, or on the structure of the smallest fly, than he 

 does at the sight of an aged oak, or at the immense bulk of an 

 elephant. Hence, we can safely say that there is no more ineffable 

 or purer pleasure than that which is afforded to him who, with the 

 aid of the microscope, investigates the marvels of minute structure 

 so eminently calculated to exalt the mind to the admiration of Infi- 

 nite Creative Wisdom. 



However, the micrographical observer does not have the gratui- 

 tous enjoyment of his satisfaction, since he has very often to en- 

 counter difficulties which must be overcome, aud has inevitable an- 

 noyances to bear. Among other things, the nricroscopist, and es- 

 pecially one who attends to the study of the Diatomacea?, finds 

 himself constantly obliged to take and to register the measures of 

 the objects which he has before his eyes, and to calculate the mi- 

 nuteness of details, which are often so small that more than a 

 thousand could be contained in the space of a millimetre. 



For taking these measures and computing the wonderful small- 

 ness of these particles, numerous are the means at the disposal of 

 the student, who, with different methods and by different ways, can 

 attain his desired object with more or less facility and exactitude ; 

 and of these I intend to treat. On such a subject I do not pre- 

 tend to say anything new ; I shall only rewrite, in a few words, as 



