DR. C. W. SIEMENS' ADDRESS. 209 



a plane, and of plane angles ; comprising geometry, trigonometry, 

 surveying, and the construction of linear measures, distance meters, 

 sextants and planimeters, of which a great variety will be found 

 within this building. 



The subject of linear measurement will, I am happy to state, be 

 brought before you by one whose name will ever be remembered as 

 the introducer into applied mechanics of the absolute plane, and of 

 accurate measure, I mean Sir Joseph Whitworth. It is to be re- 

 gretted, I consider, that Sir Joseph Whitworth adopted as the unit of 

 measure, the decimalized inch, instead of employing the centimetre, 

 and I hope that he will see reason to adapt his admirable system of 

 gauges, also to metrical measure, which, notwithstanding any objec- 

 tions that could be raised against it on theoretical grounds that, 

 namely, of not representing accurately the ten millionth part of the 

 distance from one of the earth's poles to its equator is, nevertheless, 

 the only measure that has been thoroughly decimalized, and which 

 establishes a simple relationship between measures of length, of area 

 and of capacity. It possesses, moreover, the great practical advantage of 

 having been adopted by nearly all the civilized nations of Europe, 

 and by scientific workers throughout the world. Sir Joseph Whit- 

 worth's gauges, based upon the decimalized inch, are calculated to 

 maintain their position for many years, owing to the intrinsic mechan- 

 ical perfection which they represent, but the boon conferred by their 

 author would be still greater than it is, if, by adopting the metre he 

 would remove the last and only serious impediment in the way of the 

 unification of linear measurement throughout the world. A discussion 

 will probably arise regarding the relative merits of measurement a but, 

 of which Sir Joseph Whitworth is the representative, and of measure- 

 ment a trait, which is the older method, but is still maintained by the 

 Standard Commissioners, both in this country and in France. 



The second group includes the measure of volume or the cubical 

 contents of solids, liquids, and gases, comprising stereometric methods 

 of measurement, the standard measures for liquids, and the apparatus 

 for measuring liquid and gaseous bodies flowing through pipes, such 

 as gas meters, water meters, spirit meters, of which, likewise, a great 

 variety, of ancient and modern date, will meet your eye, and upon 

 which Mr. Merrifield will address you. 



