this distance on the cover of a book, and then verify the result.
Do the same on a t.t. (test-tube). Try this several times on
different objects till you can carry in mind a tolerably accurate
idea of 10 cm. About how many inches is it?

In the same way estimate the length of 1 cm, verifying each
result. How does this compare with the distance between two blue
lines of foolscap? Measure the diameter of the old nickel five-
cent piece.

Next, try in the same way 5 cm. Carry each result in mind, taking
such notes as may be necessary.

(Fig. 1)

3. Capacity.

Experiment 2.--Into a graduate, shown in Figure 2, holding 25 or
50 cc. (cubic centimeters) put 10 cc. of water; then pour this into
a t.t. Note, without marking, what proportion of the latter is
filled; pour out the water, and again put into the t.t. the same
quantity as nearly as can be estimated by the eye. Verify the
result by pouring the water back into the graduate. Repeat
several times until your estimate is quite accurate with a t.t.
of given size. If you wish, try it with other sizes. Now estimate
1 cc. of a liquid in a similar way. Do the same with 5 cc.

A cubic basin 10 cm on a side holds a liter. A liter contains
1,000 cc. If filled with water, it weighs, under standard
conditions, 1,000 grams. Verify by measurement.