432 The Philosoj)Jdcal Instruments in the Paris Exhibition. 



was exhibited by M. Serrin, whose electric lamps for light- 

 houses are now in general use in France. This light is so 

 intense, that it has been used with great success to obtain 

 photographs of the catacombs under Paris. The applications 

 of electricity to telegraphy and horology were well repre- 

 sented, but they were not included in the department of 

 philosophical instruments. A whimsical application of mag- 

 neto-electricity was exhibited by Trouve, of Paris, in the form 

 of various quaint figures, mounted as pins, etc., which are set 

 in motion by miniature electro-magnetic apparatus. 



The beautiful and interesting phenomena of diffraction and 

 polarization have caused many ingenious contrivances to be 

 invented for their display and examination. By far the best 

 and most complete polarising apparatus was that exhibited by 

 Duboscq and Bertaud, of Paris. 



One of the most interesting novelties in philosophical in- 

 struments is the spectroscope, which has made us acquainted 

 with several new metals, and to a great extent with the solar 

 photosphere. The startling success that has attended these 

 philosophical investigations has led to the spectroscope being 

 greatly improved. Extremely fine instruments of this descrip- 

 tion were exhibited by France. The most remarkable in all 

 respects was that shown by Duboscq. The beam in this in- 

 strument is successively transmitted through six prisms of 

 sixty degrees, by which means the separation of the bands of 

 the spectrum is greatly increased. By an ingenious con- 

 trivance these prisms can be easily moved in combination. 



The recent exhibition, like that of 1862, has been very 

 complete in its display of microscopes, accessory apparatus, 

 and objects. It is gratifying to be able to record that our 

 country maintaimed its pre-eminence in these valuable in- 

 struments. The microscopes of Messrs. Beck, T. Ross, and 

 Dallmeyer were found, on trial, to be the best exhibited. As 

 was to be expected, the binocular microscope is gaining 

 rapidly in estimation. The principle generally adopted is 

 that of Mr. Wenharn's, admirable specimens of which were 

 exhibited by several makers. While willingly testifying to 

 the great excellence of our English microscopes, it is very 

 satisfactory to be able to add that the microscopes exhibited 

 by continental makers were in all respects superior to those 

 exhibited by the same makers in 1802. The microscopes of 

 M. Hartnack, of Paris, were especially good. 



It is remarkable that the continent, and especially France, 

 should not have shone in the late Exhibition in calculating 

 machines. Pascal, with whose name unwarrantable use has 

 lately been made with respect to the forged letters attributed 

 to him, invented an arithmetical machine; and Leibnitz in- 



