76 Intelligence and Miscellaneous Articles. 



try ? — All chemists use it by preference. If you refer to any of our 

 scientific journals, I think you will observe that weights are almost 

 invariably given in grammes, and measures in millimetres. 



Since the publication of the above-named Parliamentary Report, 

 a deputation has been received by the Right Hon. Milner Gibson, 

 President of the Board of Trade, to enforce the propriety of the 

 general adoption of the metric system. At this interview, Professor 

 Owen of the British Museum showed its importance in the study of 

 natural history. In this science, as he observed, the majority of 

 the facts include the elements of weight and measure. The evils and 

 inconveniences of the present state of things were illustrated by such 

 instances as the following : — 



An English anatomist and physiologist gives the weight of the 

 brain, lungs, &c. in relation to the weight of the body, of some rare 

 animal. The foreign physiologist desires to reduce the English 

 weights to those of his own country. If the kind of weight used by the 

 Englishman be not specified, viz. avoirdupois or troy, the description 

 is useless to the foreigner in regard to the important constants of 

 the proportion of parts or organs to the whole body. 



Whilst British observers vary even in the use of weights legalized 

 in their own couutry, our present systems of measures of capacity 

 make it still more difficult to impart to foreign savans the results of 

 our observations. 



As to linear admeasurements, a foreigner has generally some mis- 

 giving whether the British naturalists, in describing lengths by 

 " lines," mean the twelfth or the tenth part of the English inch. The 

 most careful describers feel themselves, therefore, compelled, for the 

 sake of their continental fellow-labourers, to make use of two systems 

 of notation ; and I have for some time used the French decimal 

 system, appending the dimensions, in parts of the metre, to the de- 

 nominations of the English system. A foot-rule, with the divisions 

 of the metre on one side, is now indispensable for associated labours 

 of observation in regard to constants of linear admeasurement. 



Although, when the system of weight or measure is noted by the 

 observer, its reduction, or the finding of the equivalent in another 

 system, is a small demand upon time, yet the repetition of that act 

 takes a serious amount from the working-hours of the individual ; 

 and when multiplied by the number of observers obstructed by con- 

 flicting systems of weights and measures, the impediment to the 

 progress of the sciences of observation become so great as to render 

 the subject quite worthy of the consideration of legislative authority. 



EXPERIMENTAL DETERMINATION OF THE VELOCITY OF LIGHT : 

 DESCRIPTION OF THE APPARATUS. BY M. LEON FOUCAULT. 



Spite of restricted space and of the want of figures, I shall try 

 to describe the principal parts of the apparatus which has yielded a 



