10 Scientific Proceedings, Royal Dublin Society. 



system of measures in competition with the metric system ; or 

 could entertain the least idea that it would ever become a universal 

 system, employed by the whole civilized world, such as the metric 

 system will become if it is adopted by the English-speaking 

 populations of the world. Nor can we come to any other con- 

 clusion than that this is fortunate ; since of the two systems, the 

 metric system is distinctly the better for the whole future of the 

 world, on account of the more useful relations established in it 

 between measures of length on the one hand, and the weights and 

 measures of surface and of capacity on the other. 



There is another considerable practical advantage which 

 attaches to metric measures of length, to which the attention of 

 the present writer was called, nearly fifty years ago, by the late 

 Dr. Humphrey Lloyd, Provost of Trinity College, Dublin. It 

 depends on the magnitude of the millimetre, which is the smallest 

 division placed on the metric rules used by artisans. The milli- 

 metre, though small, is so conspicuous to the eye on such rules that 

 the workman measures, with extreme ease, to the nearest millimetre 

 when making very rough measurements. This is a better measure- 

 ment than is usually made in rough work with workmen's English 

 rules. And the millimetre is also nearly the smallest interval 

 that can be correctly subdivided into tenths by estimation. When 

 one uses metric scales much, one insensibly acquires the power of 

 dividing any length into tenths by estimation, with a remarkable 

 approach to accuracy. This useful power, when once acquired, 

 makes it possible for a workman, using a metric scale, to measure 

 lengths to the nearest tenth of a millimetre, rapidly, with the 

 naked eye, and without verniers. This is much greater precision 

 than can be attained with the rules commonly employed by 

 workmen in this country. The tenth of a millimetre is nearly the 

 smallest interval that the unassisted eye can see. It is about the 

 average thickness of sheets of paper. 



What then is our present position in England in regard to 

 weights and measures, and what are our prospects ? 



An Act was passed in 1864 which purported to make it lawful 

 to use metric weights and measures in the United Kingdom ; but 

 it was held by our courts of law that it did not attain its object, 

 because it did not recite and repeal a clause of a preceding Act 

 which forbade the use of any other than imperial measures in 



