ABSTRACT
A clearer picture of the growing importance of minerals in American manufacture may be seen from a study of the growth of physical output. Essential to mass production were the progress of technology and invention, the availability of adequate capital, and a national market big enough to absorb the product, for mass production was based upon mass consumption. Mass production based on the assembly line was mainly responsible for the reduction of the base price of the Model T from $950 to $290. Two causes account for the significant shift in power: first, the superiority of electric power in convenience and cost for many industrial producers; second, technical advances in electricity which made the whole change possible. Industrial improvements were particularly noteworthy in photographic appliances, office equipment, and building materials, and in the combinations of photography and electricity which have produced the moving picture. Industrial research, according to Jewett grew ten times between 1915 and 1918.
