160 REPORT — 1865. 



aluminium bronze. It is sufficiently hard ; it is fusible, and takes good inpressions 

 in the mould ; it shows fine and clear lines on being engraved*. 



II. Form and Dimensions. — I propose that the instrument should be 102 centi- 

 metres long, 6 centimetres broad, and 1 centimetre thick. The reasons for adopt- 

 ing these dimensions will be explained in the sequel. 



TTT. Description by means of Letters, Figures, and other marks. — For the com- 

 position and arrangement of these I am indebted to Mr. Frank Fellows. 



The yard is placed above, the metre below. Above the yard is its description, 

 in these words: "Yard divided into Feet and Inches," after which the title of the 

 Act of Parliament is quoted, by which Act the yard is defined, and its legality 

 established, viz., "5 Geo. IV. ch. 74." The space* on which these titles are to be 

 inscribed is proposed to be 1 centimetre broad. 



The antithesis to this space is that at the bottom of the instrument, also 1 centi- 

 metre broad. It describes the measure immediately above it, and the Act of Parlia- 

 ment by which that measure is denned, and its legality established : " Metre divided 

 into Decimetres, Centimetres, and Millimetres. — 27th and 28th Victoria, ch. 117." 



The middle breadth of 4 centimetres is equally divided between the yard and the 

 metre. Each of these has a space of 2 centimetres broad, and the space belonging to 

 each is again divided into equal breadths, each of which has consequently a breadth 

 of 1 centimetre. The space belonging to the. yard is a yard long, and is intended to 

 be the exact measure of a yard. The space beneath it, and contiguous to it, belong- 

 ing to the metre, is, in like manner, intended to be the exact measure of a metre. 



The upper half of the space belonging to the yard, being a centimetre broad, is 

 divided lengthways into 3 feet ; the lower space, also a centimetre broad, is divided 

 into 36 inches. Thus far the division is that appointed by Act of Parliament. But 

 we have thought a further subdivision expedient, through a small portion of the 

 scale, viz., the division into eighths of an inch. "We have chosen eighths rather 

 than tenths or twelfths of an inch, because eighths are far more extensively in use, 

 and also some persons of eminence and high authority in this country think a binary 

 much preferable to a decimal or duodecimal division. 



Proceeding on the same principle and in strict conformity with the law of the 

 country, we divide the metre lengthways into decimetres, centimetres, and milli- 

 metres. But whereas the yard has the greater divisions placed above and the 

 smaller divisions below, we have in the case' of the metre placed the smaller divi- 

 sions above and the larger below. This arrangement produces great facilities for 

 comparison, because it brings the small divisions of the two scales into immediate 

 apposition. Thus we fiud as approximations, — 



One eighth of an inch = 3 millimetres. 



One quarter „ = 6 millimetres. 



One half „ = 12i millimetres. 



One inch = 25 millimetres. 



Two inches = 50 millimetres. 



Four inches = 100 millimetres. 



For greater exactness reference may be made to Packard's Ready Reckoner, or 

 Dowling's Comparative Tables. 



It is necessary to observe that both of these scales begin from the left hand, and 

 from the same perpendicular line. 



The spaces at the two ends of the instrument, which are extraneous to the 

 yard and metre scales, are each half a centimetre wide. They will serve as 

 guards to the two 'scales. The name of the maker of the instrument mav be 

 engraved on the right hand. If the manufacture of these standards is entrusted 

 to well-qualified persons, if they are provicfed with exact standards for their 

 own use, and if they bestow due pains and care on those which they produce, 

 the standards of their making will be sufficiently accurate for all common prac- 

 tical purposes, and there will be no necessity to seek assistance in providing lineal 



* Notwithstanding these real or supposed advantages, the use of Baily's metal has been 

 abandoned in favour of the adoption of glazed or enamelled porcelain. 



