As trade and intercourse between different peoples developed, the need for an orderly system of measurements made itself felt. The endeavour to create invariable unite as standards of measurement could be traced back to this period of cultural development. However, the task of finding a material measure, which would remain invariable at all times and from which, therefore, the original unit or standard could be retraced at any time, had. not been completed up to the present time. A. system of measurements isthe better, the simpler and moor complete the interconnection of the ferent units which constitute it This postulate was well-known to the ancient Chaldeans and Baby-ionians, whose system the lecturer explained and showed how clear a conception these ancient savants had of the necessity of interconnect ing the different units of their sys tem of measurements, Through trade, the units of their system were carried into other countries.
These nations, however, not knowing the exact relations between the different units, had no means to check them and all they could do was carefully to preserve them. These units did not remain constant, but gradually changed in the course of time and, therefore, did not comply with the postulate of variability. This process went on until, in the Middle Ages, the systems in use had become so complicated and the units changed so much from place to place that a uniform system became in almost every country a crying need.
The lecturer confined himself to showing the development of the standard units in both the British and French systems of measurement, the latter especially because it had become of international importance. In the British system, he traced the standard of length back to King Henry I in 1101. He showed that legislation had occurred prior to King Edward I, but that the "yard," or unit of length, had been defined independently at different times, Ho read passages from the old Act, showing how the length standard had been defined at that time, The history of the mass standard, the "pound," was similar. "Pounds" had been defined at different times but not until as recently us 1824, The standard of capacity, the "gallon," although not strictly necessary and really a derived unit, also was defined by the Act of 1824, The standard yard constructed by the Parliamentary Committee of 1758 and legalized by the Act of 1824 was based on a brass yard made by order of Queen Elizabeth in 1687, which is preserved at the Board of Trade, and agrees with the present standard yard within tone hundredth of an. inch. The yard of Henry VII differs from the present legal standard by 2 hundredth of an inch.
The present legal standards were constructed after the destruction by fire in' 1884 of the standards authorized ten years earlier. The lecturer showed how complicated was this reconstruction, which occupied 21 years. Several so-called Parliamentary copies were made and carefully compared with the imperial standards preserved in the office of the Exchequer, so that their small and inevitable errors are known, They were adopted in 1865 and from the secondary standards of the British system and they were deposited, one in the Royal Observa~ tory at Greenwich, one in the Royal Mint, one with the Royal Society, and the last one was immured in the new palace at Westminster. In 1866 the custody of the imperial standards was transferred to the Board of Trade. The lecturer referred to the various acts that have changed the relation between the pound avoirdupois and the troy pound up to the present time.
The Metric System The history of the metric system is far less complicated and started the time of the French Revolus tion in 1792, Owing to the horribly confused state' of the French measurement systems of that time, Talleyrand's proposal before the ational Assembly, 1790, to revise and regulate the measurement sys tem found warm support. The commission formed for the purpose of investigation consisted of Boarda, Lagrange, Laplace, Mongo, and Gondoreet, and decided against the idea of the National Assembly to use the length of the second pendulum and adopted instead the ten-millionth part of the earth quadrant, under the name of
Text read from the printed page and cleaned; old type leaves the occasional error.