Standard Metre--Unit of wave-lengths preferable--The
International Metre

§ 3. The Measure of Mass: Distinction between
mass and weight--Objections to legal kilogramme
and its precision--Possible improvement

§ 4. The Measure of Time: Unit of time the
second--Alternative units proposed--Improvements in
chronometry and invar

§ 5. The Measure of Temperature: Fundamental
and derived units--Ordinary unit of temperature
purely arbitrary--Absolute unit mass of H at pressure
of 1 m. of Hg at 0° C.--Divergence of thermometric
and thermodynamic scales--Helium thermometer for low,
thermo-electric couple for high, temperatures--Lummer
and Pringsheim's improvements in thermometry.

§ 6. Derived Units and Measure of Energy:
Importance of erg as unit--Calorimeter usual means of
determination--Photometric units.

§ 7. Measure of Physical Constants: Constant of
gravitation--Discoveries of Cavendish, Vernon Boys,
Eötvös, Richarz and Krigar-Menzel--Michelson's
improvements on Fizeau and Foucault's experiments--
Measure of speed of light.