I inclose (1) a tabulated summary of the estimates for Birmingham divided into stages of 3,000 gross indicated horse power at a time; (2) a statement showing the cost to consumers in terms of indicated horse power and in different modes, more or less economical, of applying the air power in the consumers' engines; (3) a tracing showing the method of laying the mains; (4) a tracing showing the method of collecting the meter records at the central station, by means of electric apparatus, and ascertaining the exact amount of leakage. A short description of the two latter would be as well. TABLE I.--_Showing the Progressive Development of the Compressed Air System in stages of 3000 Indicated Horse Power (gross) at a Time, and the Profits at each Stage_ _____________________________________________________________________________ Gross | 3000 | 6000 | 9000 | 12,000 | 15,000 | Indicated | Ind. | Ind. | Ind. | Ind. | Ind. | Horse Power | H.P. | H.P. | H.P. | H.P. | H.P. | at Central | | | | | | Works: | | | | | | ----------------------------------------------------------------------------- Thousands of | 1,080,000 | 2,160,000 |3,240,000 | 4,320,000 |5,400,000 | Cubic Feet at 45 | | | | | | lbs. pressure | | | | | | at engines | | | | | | Deduction for | 17,928 | 70,927 | 154,429 | 267,529 | 409,346 | friction and | | | | | | leakage | | | | | | Estimated net | 1,062,072 | 2,089,073 |3,085,571 | 4,052,471 |4,990,654 | delivery | | | | | | -----------------------------------------------------------------------------