428 The Philosophical Instruments in the Paris Exhibition. 



Exhibition was excellent. The great desideratum of attaching 

 an effective artificial horizon when the sea-line is obscured, may 

 be said to have been attained. Eminent makers of optical 

 instruments will always supply a good and reliable sextant ; 

 but we may observe that no English mariner need now go to 

 sea in doubt respecting the performance of his sextant, as the 

 British Association for the Advancement of Science have 

 organized measures by means of which sextants can be efficiently 

 tested at the Kew Observatory. 



The surveying instruments exhibited were greatly superior to 

 those at the Exhibition of 1862. With the theodolite, which is 

 certainly the fittest instrument for measuring terrestrial angles 

 with precision, and which has displaced the separating circle on 

 the continent, very great pains have been taken to obtain pre- 

 cision with compactness. The theodolites exhibited by London, 

 Paris, Berlin, and Vienna makers were admirable, as also were 

 those shown by J. Kern of Aarau in Switzerland, who employs 

 many hundred hands in making these and other instruments. 

 The Industrial Institution of Lisbon also exhibited several well- 

 made theodolites. A very ingenious stenographic and ortho- 

 graphic machine was exhibited by Cavaliere Eossi of Rome, 

 with which he has made a very trustworthy survey of the 

 catacombs under and around that city. A very good display of 

 telemeters and planimeters was made by France and Prussia, 

 both of which nations have used these instruments extensively 

 in field operations during war. 



A very large display by various countries was made of 

 mathematical and drawing instruments. Those exhibited by 

 Elliott Brothers, maintain in all respects the high character of 

 their house. Excellent instruments of this description were 

 also exhibited by Gravet-Tavernier of Paris, J. Kern of Aarau, 

 and Haff of Munich. The extremely low price of the instru- 

 ments by these makers, as compared with those made in 

 England is very remarkable. The Swiss and Bavarian makers 

 sell a magazine case of excellent instruments containing a beam 

 compass, proportional compass, six pairs of ordinary compasses 

 of various dimensions, several excellent drawing pens, graduated 

 rulers, sectors and protractors, all in electrum metal, for 

 £o 1 8s. The United States of America, which formerly imported 

 nearly all their dividing-engines and mathematical instruments, 

 now manufacture largely and well. The instruments exhibited 

 by Darling, Browne, and Sharpe, of the above country, are 

 admirable. The accuracy of their steel straight-edges is very 

 great, and the divisions on all their scales, which are effected 

 by machinery, are extremely clear and accurate. These articles 

 are manufactured very largely for the engineering establish- 

 ments of the United States, and also for the English market. 



