7 
the available data on utilisation were used,by means of the 
production index, to calculate the implicit indes of capacity. 
The results were then compared with the data on gross capital 
stock. This showed for some countries such as the U.S. 
a lesser growth of capacity which was interpreted as 
a shortening of the life-time of equipment. This attempt 
to make explicit the implications of a very shaky data 
basis throws some light on our ignorance in this field. 
We know much less about capital eqqipment than demographers 
know about people. We have no statistics at all about 
scrapping (death) and our ideas about the length of life 
are rather conventional. The assumption of a constant length 
of life underlies all statistics of the capitla stock. 
The concepts of capacity and utilisation as well as the 
empirical data need considerable study. This would also 
give opportunity for interdisciplinary work ( cooperation 
with engineers to obtain technical expertise ). 
The importance of the capacity concept has also been suggested 
by Roncaglia when he spoke of the distinction between 
classical and Keynesian unemployment. Classically unemployed 
are those who can not be employed for lack of capital - 
for what I would call employment capacity in contrast to 
output capacity which is the usual meaning of "capacity". 
Roncaglia suggested that classical enemployment is 
being created by the policy of restricting demand because it 
leads to a deficiency of investment. ( Perhaps the neglecjit 
of investment in "human capital" is even more grave ). 
But a lack of capacity may arise also from 
demographic reasons: At the end of the second period there 
was a substantial increase in the growht rate of the labour 
force in the U.S. The reasons were higher birth and