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4 



• 1 



Miscellaneous Intelligence. - '441 



constantly upon their knife edges wLen the beam is resting upon its 

 supports. On the whole, therefore, while doing full justice to tlie ad- 

 mirable workmanship of Oertling\s instrument we must give tlie pref- 

 erence to Deleuil's larger balance ^ox physical investigations, regardint'- 

 always the smaller balances of Oertling^s as superior to all olliers in- 

 tended for chemical researches. Of the English balances ihe only 

 t)ne worth noticing is that of L. Oertling of London ; the beam of this 

 instrument is very light and the instrument 'would appear to be a good 

 one, but its shape is inelegant and the want of the sliding rod arrange- 

 nient is a serious inconvenience. The Danish, Swedish and Be/gran 

 balances do not deserve notice ; the superintendent of the U. S. Coast 

 Survey exhibits two balances by Mr. Saxton, a larger and a smaller, 

 but the construction of these is too well known in this country to re- 

 quire description at our hands ; ihey are at least equal in point of work- 

 manship to any which the writer has seen abroad. 



Of optical apparatus the display in the exhibition is upon the whole 

 y^vy good. M. Duboscq,* son-in-law and successor of Suleil, exhibits 

 a very fine collection of optical instruments, among which we noticed 

 as of recent introduction, Duboscq's regulator of the electric light, 

 and Jamin's instrument for the study of the plienomena of reflection 

 at transparent surfaces. The Nicol's prisms, rhombs and spheres of 

 Iceland spar, and glass prisms executed by Bertrand,t are the finest 

 specimens of workmanship in this department which we have ever wit- 

 nessed. Of glasses for optical purposes there are many interesting 

 specimens. Messrs, Chance of Birmingham exhibit discs of flint glass 

 eighteen, and of crown glass twenty-four inches in diameter; (he flint 

 discs appeared to be of fair quality, but we had no opportunity of ex- 

 amining ihem closely as to veins and strice; the crown glass was of 

 bad color, indicating want of purity in the materials. The new French 

 glasses with bases of zinc and baryta are admirable, and of perfect 

 transparency and high refractive power; the discs for optical purposes 

 though not so large as the English ones were of perfect qualify, and 

 an opportunity of examining them closely was freely given. Several 

 discs, and prisms of flint glass from T. Daguet of Soleure in Switzer- 

 land also deserve notice. The only thermometers and barometers 

 adapted for scientific investigation were those of Fast re ;|: the ther- 

 niometers are constructed in exact accordance with the method of 

 Begnault, being furnished with arbitrary scales and divided upon the 

 stems themselves: the barometers are constructed nearly upon the 

 plan of Foriui, In connection with these instruments we may men- 

 tion the straight line dividing engine of Perreaux,§ now generally used 

 in the French physical laboratories. Of these there are two sizes, one 

 for the graduation of lines not exceeding 70 centimeters in length, 

 (price with microscopes for revision 900 h.) the other for lines not ex- 

 ceeding 45 centimeters, (with microscopes 500 fr., without them 400 

 fr.) Of the very large number of electric telegraphs exhibited, there 

 were we believe none which employed principles essentially diflerent 



♦ Duboscq, Rue de VOdeon, 35. f Bertrand, Jr., 32 Bue de Bretagne. 



Fastr^, Rue de I'ecole Poljtechnique,^ 3. 

 Perreaux, Rue M. Lcpriuce, 14. rari^i. 





