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1:.
THE METRIC SYSTEM 5
the other, the position being reversed, depending on the
location of the operation (Fig. 54). The practice of the
proper rests and guards is important and should receive
close attention in the technic laboratory at the same time
that the study of instrument grasps is begun.
The Metric System of Measurement
Before taking up the study of instrument forms and their
manufacture, it is necessary for one to have a knowledge of
the metric system of linear measurement and the centigrade
circle, together with their method of adaptation to the tak-
ing of the measurement of the various parts of instruments.
The metric or French decimal system is the one now
adopted by most scientific men and the reader should
begin at once to put its principles into use. It is based on
the French meter, which equals 39.37 inches in the old
measurement. The denominations of the system may be
learned here, but the only method of thoroughly appreciating
them is to put them into actual practice. These denomina-
tions, so far as their uses in dentistry require, are as follows
One Meter 39 inches (approximate).
One Decimeter (one-tenth of a meter) 4 inches (approximate)
One Centimeter (one-hundredth meter) % inch (approximate).
One Millimeter (one-thousandth meter) 3^5 inch (approximate).
Tenths, hundredths and thousandths of a millimeter.
One thousandth of a millimeter is known as a micron and is used only in microscopic
work.
(Table from Black's Operative Dentistry.)
The Centigrade Circle.—This is a circle divided into one
hundred parts or degrees, instead of 360°, as is the astronom-
ical circle. To convert centigrades, the degrees represented in
this circle, into astronomical degrees, multiply 360 by the num-
ber of centigrades and divide by 100; or (a simpler method)
THE METRIC SYSTEM 5
the other, the position being reversed, depending on the
location of the operation (Fig. 54). The practice of the
proper rests and guards is important and should receive
close attention in the technic laboratory at the same time
that the study of instrument grasps is begun.
The Metric System of Measurement
Before taking up the study of instrument forms and their
manufacture, it is necessary for one to have a knowledge of
the metric system of linear measurement and the centigrade
circle, together with their method of adaptation to the tak-
ing of the measurement of the various parts of instruments.
The metric or French decimal system is the one now
adopted by most scientific men and the reader should
begin at once to put its principles into use. It is based on
the French meter, which equals 39.37 inches in the old
measurement. The denominations of the system may be
learned here, but the only method of thoroughly appreciating
them is to put them into actual practice. These denomina-
tions, so far as their uses in dentistry require, are as follows
One Meter 39 inches (approximate).
One Decimeter (one-tenth of a meter) 4 inches (approximate)
One Centimeter (one-hundredth meter) % inch (approximate).
One Millimeter (one-thousandth meter) 3^5 inch (approximate).
Tenths, hundredths and thousandths of a millimeter.
One thousandth of a millimeter is known as a micron and is used only in microscopic
work.
(Table from Black's Operative Dentistry.)
The Centigrade Circle.—This is a circle divided into one
hundred parts or degrees, instead of 360°, as is the astronom-
ical circle. To convert centigrades, the degrees represented in
this circle, into astronomical degrees, multiply 360 by the num-
ber of centigrades and divide by 100; or (a simpler method)
