196 The Stock Market Crash—dAnd After 
science into business management, trade union policy, 
and government administration. Concrete instances 
of technical improvements in many mining, metallur- 
gical, and fabricating processes are given in the chap- 
ters on industry. The remarkable results achieved 
are demonstrated statistically from census data show- 
ing output per worker. Similar, though less strik- 
ing, instances appear in the chapter on construction. 
Without help from any extraordinary invention, the 
railroads, also, have attained a higher level of op- 
erating efficiency. In farming there is an intriguing 
report of new machines and new methods coming 
into use. Here, too, the record of average output 
per worker shows considerable gain. 
“All this means that since 1921 Americans have 
found ways of producing more physical goods per 
hour of labor than ever before. They have received 
larger average incomes because they have produced 
more commodities and services.” 
It was in this intensified upthrust of forces mak- 
ing for increased productivity per worker during the 
past seven years that the secret of the long bull mar- 
ket stands revealed. From this increased produc- 
tivity came a more rapid increase of earnings of 
corporations, together with the ‘“‘plowing-back” of 
earnings in expectation of greater future gains. This 
expectation made men content to invest their money 
for smaller immediate dividends and at higher prices 
for corporate securities than past earnings had 
warranted. 
A further reason was in the reduction of risks due