The 1845 Troughton & Simms rule was replaced in 1874 by two new "Dominion Standard Yards" (880251), which were also made by T&S.

The right end of the "B" copy of the Dominion Standard Yard. This, like the 1845 yard, was made of Baily's Metal. The depressions in each end are where marks (+) are scribed to indicate the exact length of the standard. The lines are so fine that many people need a microscope to see them. Two of the wax seals found on the case help establish the history of this particular measure.

Our example is the one which was held by the Senate of Canada — demonstrating the importance with which such devices were viewed. The wax seals that survive on the case add to its interest, and help trace the provenance of this artifact. This artifact — and many other primary standards from the twentieth century — has been acquired from the National Research Council (NRC). Many of the other artifacts seen here were acquired from Measurement Canada.

In the 1880s, with the spreading use of gas for light, heat and commercial power, it became necessary to expand existing standards to include regulated measures for gas. The Museum's collection includes various devices for this purpose, the most interesting of which are the gas calorimeter (970229) and the gas flow prover (970227).

The gas calorimeter (970229) made by Alexander Wright & Co., circa 1900, was used to determine the calorific or heat content of a given measure of gas at a specified temperature. This apparatus was one of the first to employ a recording device.

Gas flow prover (970227) manufactured by Alexander Wright & Co., circa 1910. A quantity of air was passed from the prover through the meter to determine if the registration agreed. A few of the brass fittings are missing, but it is still an impressive apparatus.

The calorimeter was used to verify the energy content of the gas; the prover was used to test or "prove" that gas meters were accurately registering the amount of gas flowing through them.

In 1901, Otto Klotz — an astronomer then with the Geodetic Survey of Canada — wrote about the history of metrology in Canada, lamenting the lack of any lab equipped to scientifically maintain and compare the standards used in Canada. Taking this concern seriously, within a few years the federal government had purchased a large quantity of new apparatus for the Department of Inland Revenue. Purpose-designed labs — such as that at the Geodetic Survey of Canada — were also established, and new standards were acquired.

Standardization Lab (1913) of the Dominion Lands Survey Department in Ottawa incorporates a comparator, reading microscopes and screws for endwise adjustment of a 1-metre standard rule made of invar–a low-expansion alloy. This, in turn, was used to verify the 1–4-metre rules used by surveyors Thermographs to monitor temperature in the lab (F) may also be seen on the walls.

The metric system had been established in 1795, and the International Bureau of Weights and Measures in Paris was established in 1875. In 1884, the metric system became legal in Great Britain, and thus also legal in Canada. Canada became an adherent to the "Convention of the Metre" in its own right in 1907, although it would be many years before the metric system replaced Imperial measurements. The official switch to metric measurement occurred in 1971; however, in 1984 both metric and Imperial measures were made legal. Our secondary standards for metric volumes (970080) date from after 1873. Related is a standard metre (970076), which was employed as a secondary length standard in Canada from 1909 on.

Metric volume measures (970080) were purchasedby the Canadian government in ca. 1874. This was the first time when conversion to the Metric system ws being considered by Britain and Canada. The Museum's set were made by Collot Frères of Paris.		1909 Standard metre (970076) by W. & T. Avery of Birmingham, England. Note the wooden knobs that screw onto the bar, enabling it to be lifted from the case and insulated from the heat of the user's hands. This standard was probably acquired as a result of Canada's membership in the 1907 "Convention of the Metre".

The collection's post-1900 apparatus also include three impressive sets of masses: one based on Troy ounces (970163), one on Avoirdupois ounces, and the other metric (970162 and 970161, not illustrated). Each set of 23 or 24 masses is protected by three oak cases. All were made by L. Oertling in London.

One of the three cases for the 1912 set of masses (970163), based on Troy ounces. These served as secondary standards for Canada until 1969 with the cases marked "C". The primary, or "A", metric set (970098), dated 1909, is also in the Museum's collection. All were made by L. Oertling in London.

One role Legal Metrology retained until the 1970s was the verification of the "Pyx": an annual trial in which samples of silver dollars produced by the Royal Canadian Mint were weighed to ensure that they contained the legally-prescribed amount of silver. This was a very formal event, and the scales and weights used for the trials received special care and attention. The Oertling balance (970131) shown here was the one reserved for this function and ceremony.

The Pyx balance was made around 1930 by Oertling in London. It was used annually until the 1970s, to verify the silver content of Canadian coins during an official ceremony called the "Trial of the Pyx". The term "Pyx" came from a letter by Sir Isaac Newton on procedures to be used while he was Master of the Mint.

Some of the first electrical equipment to regulate meters in the spreading electrification of cities and towns was acquired ca. 1910-1915 as well. A Kelvin's electric balance (970093) was used as a secondary standard at the NRC from ca. 1920 to measure resistance and electric current, while a Drysdale's potentiometer (840664) was used by Inland Revenue to measure AC and DC voltages and currents.

Lord Kelvin's current balance (970093) used two electrical currents flowing through two sets of wire coils. This created opposing magnetic fields above and below two plates attached to the balance arm (silver arm in front). The balance of the arm was adjusted with small weights, in order to bring the front arm to the 0 position. The amount of weight this required gave a direct comparison of the two currents flowing in the coils.
		This Drysdale potentiometer (840664) was made by H. Tinsley & Co. in London, sometime between 1898 and 1905. It was employed to measure AC and DC voltages and currents in electrical circuits, including equipment being tested.

The voltmeter (970090) was used as a laboratory standard to determine the DC voltage in circuits where instruments were being tested.

A laboratory standard DC voltmeter (970090), used to monitor voltage in test circuits. Note the thermometer to the left of the meter's bottom left corner. This was used to record temperature for correction to a standard value. Made in the 1920s by Weston Electrical Instrument Co., Newark, N.J.

Before long, Inland Revenue was acquiring, testing and approving every type of power consumption meter for use in Canadian homes and businesses. The "Demand Energy" power meter (840550) is an example of this type of device.

Lincoln-Sangamo demand-watt power meter (circa 1920), recording energy use in kilowatt-hours or kilovolt-amps. New types and models of electrical meters used in Canada were required to be deposited with Inland Revenue (later Legal Metrology, now Measurement Canada). These meters were tested for accuracy and required approval before they could be used commercially.

Until recently, these had to be retained by Measurement Canada by law, but many have now been preserved in the national collection at the Museum. Most were made in Canada, but examples from other countries were acquired, tested and compared with domestic meters, and several of these have been preserved at the Museum.