5,000 cycles per sec., fairly satis- factory results. In the period 1r911—24:— Annual Average | 1881-1890 1891-1900 IQOI-IQIO IQII—-1920 og 8 | 3,430] 1,264] 1,500] 389 | 30 5 53 39 8 47 38 I5 d 2 98 26 = 22 52 994 TABLE II. Marketing Costs Percentage on Sales Wholesale Retail Low- | High- | ,- Low- | High- | ,- Low- | High- est me Usual est est Usual % Yo % % % i 0 20-25 242