NovEMBER 1, 1918] 
made it apparent to us in the case of air, and 
Galileo first showed it there by experimental 
means—weighing compressed air—which ap- 
peal to other senses and to the reason. The 
savage laborer would have a rough idea of 
equality in his backloads, he might recognize 
this equality in backloads of venison or fire- 
wood, he might count backloads, bucks or 
arrows, and so attain crude notions of ratios, 
and in all things he would perceive the demand 
for effort, and so recognize the existence of 
heavy matter of all sorts; the sorts all being 
alike only in this effort-demanding quality. 
Knowing effort only through the sensations 
of effort, which are subject to Weber’s law, 
and through that form of hysteresis called 
memory, we can compare efforts, and the 
weights to which they correspond, only very 
erudely for equality, practically not at all for 
ratio, and with diminishing accuracy after 
longer intervening times. However, efforts 
being apparently equal, so are weights assumed 
to be, and, vice versa, bodies of like material 
and the same size are taken to have equal 
weights without “hefting them.” One rabbit 
is about as big and so weighs about as much 
as another. 
That two rabbits weigh twice as much as 
one, however, is not an experience, but a 
judgment. The effort sensation for two rab- 
bits is not in any sense double that for one; 
if a man can lift a side of beef with great 
effort, is the effort required to lift two sides 
at once twice as great, when he perhaps can 
not lift the two sides at all? Is the effort 
made by a stronger man who lifts the two 
double that of the weaker lifting one? 
A very ancient method of bearing loads, 
dating back to prehistoric times and portrayed 
in the most ancient records, is the carrying 
stick or yoke. Convenience and comfort in 
using this are greatest when the bearer is at 
the center, which is when equal numbers or 
volumes of like things swing from the two 
ends. This, I suppose, led to the invention of 
the balance with equal arms as a more refined 
and objective, more “honest,” means for the 
inverse purpose of testing equality in respect to 
this effort-demanding quality, weight or quan- 
SCIENCE 
429 
tity of matter. One Greek name for the bal- 
ance is fvyév, yoke; but the implement itself 
dates to measureless antiquity. H. L. Roth,t 
quotes Mr. Ivan Chien, of the Chinese Lega- 
tion in London, to the effect that Chinese his- 
tory assigns the making of scales to the reign 
of the Emperor Fu Hi, B. c. 2956. Baumeister 
(Denkmiler) says it was known in Homeric 
times; excavations in Crete show that in the 
recently uncovered civilization of its people 
the balance was used; Egyptian hieroglyphics 
show it in ancient use. As the beam was 
commonly of wood it has not been preserved 
from those early days. 
But why should people desire a more ob- 
jective, more honest, means of comparing 
things than by “hefting” or counting? I 
take it, because of trade, whose routes were 
marked in Europe even in the Stone Age (as 
is known from the migration all over the con- 
tinent of flints of identifiable origin). When 
the trade in metals grew up, accuracy and 
standards became of an importance hitherto 
unprecedented and with them arose the bal- 
ance and calibrated weights. Lepsius? is re- 
ferred to as figuring a sliding weight on a 
balance beam of ancient Egypt; I have not 
seen the figure; one would assume that such a 
sliding weight, serving perhaps as a handy 
tare, might have suggested the next improve- 
ment in weighing apparatus, the steelyard. 
Whether it did or not must remain for a while 
unknown; for the only authorities accessible 
to me are irreconcilably in contradiction as to 
the date earliest recorded of the Roman steel- 
yard. 
There are two forms of steelyard, the Danish 
and the Roman. The former seems once to 
have been very common. Sdkeland® describes 
a large variety, from simple clubshaped sticks 
to elaborately worked metal pieces. It was 
slung by a cord; the unknown weight hung 
from another cord fixed near one end, and the 
more or less heavy knobbed or swelling end 
beyond the fulerum balanced the unknown. 
1 Jour. Roy. Anthrop. Inst., 47, 1912. 
2 Denkmiiler, III., 39, No. 3. 
3 Translated in Smithsonian Annual Report, 
1900, p. 551. 
