Mathematics, 365 



success, to form a new system of Mineralogical 

 Characters, on the principles of geometry; and 

 M. Hauy, of the same country, has given a most 

 elaborate and plausible system of doctrines on 

 Crystallization, which all proceed upon fixed 

 mathematical rules. 



To this chapter belongs some notice of the at- 

 tempts which were made, during the period under 

 consideration, to ^^ on an universal and uniform 

 Standard of Measure. Such a standard has been 

 considered a grand desideratum, ever since men 

 began to speculate on subjects of this nature ; but 

 probably in no former period was it ever an object 

 of so much attention, and of such diligent research, 

 as in that which we are now reviewing. And 

 though none of the attempts to obtain a standard of 

 this kind have been attended with complete suc- 

 cess, yet several of them were so ingenious, and 

 engaged so much of the inquiry of scientific men, 

 that they ought not to be passed in silence. 



HuYGENS, the celebrated Dutch Astronomer, 

 about the middle of the seventeenth century, seems 

 to have first proposed the length of a Pendulum vi- 

 brating in a given time, as a standard of measure. 

 He proposed to take a pendulum that should vi- 

 brate seconds, to m.easure it from the point of sus- 

 pension to the point of oscillation, and to assume 

 the third part of such a pendulum, under the deno- 

 mination of an horary foot, as a standard to which 

 the measure of all other feet might be referred. In 

 1779, Mr. Hatton, of Great-Britain, undertook 

 to improve on the principle of Huygens, by apply- 

 ing a moveable point of suspension to one pen- 

 dulum, so as to produce the same effect that would 

 result from the use of two pendulums, the dif- 

 ference of whose lengths was the intended mea- 

 sure. Mr. Whitehurst, also of Great-Britain, 

 considerably improved upon this idea, in his tract 



