V

obtain the qualities of such materials in theserespects; and there may be found hereafter, inthe reports of that assembly, standards to de-termine these relations of them as well as thoseof size and weight. It cannot be* expected thatthese desiderata will be obtained directly by in-dividual exertion ; nor indirectly by individualdisgrace, by a record of repeated failures. Theexpense of such an investigation would be amplyrepaid in the first work of importance subse-quently erected.

The substance of the Parliamentary Reportof the Commissioners appointed by His Ma-jesty to consider the subject of weights andmeasures, of the 15th of March, 1821, and ofthe select committee of the 28th May, 1821,determining the standards of length, capacity,and weight, tables of weights and measures ofdifferent countries, and a table of the strengthof various materials, showing the modulus offracture of each, are given.

The column of the specific height of the key-stone of an arch in the tables of bridges mayperhaps place the subject of bridge-building in apoint of light in which it has not yet been viewed;and, in the absence of sufficient experiments todetermine the strength of stone, wood, and iron,in compression, it may enable the builder toobtain practically the height of a keystone orframe of an arch, and to adjust deductions ob-

a 3