_Depreciation and Insurance_: Aëroplanes. Useful life, say 3 years, as for airships. Obsolete value, say, $30,000 per machine. Average total depreciation per annum for 28 machines $5,250,000 Aëroplane Sheds. Total annual charge 60,000 Workshops and Plant. Depreciation at 3% per annum 3,000 Total annual charge for depreciation 5,314,000 Total annual insurance charges on machinery and plant 1,152,000 _Annual Establishment Expenses_: Salaries of 36 pilots at $3,000 per annum $108,000 Salaries of 36 engineers at $2,000 per annum 72,000 Salaries of 12 stewards at $1,500 per annum 18,000 Salaries of establishment-- Management and staff 25,000 Workshop hands and storekeepers, etc., 100 off 100,000 -------- Total annual establishment expenses $323,000 _Repairs and Maintenance_: Sheds and plant, annual charge, say $25,000 Repairs and overhaul to machines 50,000 -------- Total. $75,000 ---------- Total annual charges on above basis $8,792,500 _Cost chargeable per crossing_: Proportion of annual charges per crossing $7,250 Petrol used per trip, 28 tons at $125 per ton 3,500 Oil per trip, 2 tons at $200 per ton 400 Cost of food per trip for 29 passengers and crew of seven 500 ------- $11,650 It will be seen from the above that the direct running cost is 38%, and the overhead charges 62% of the total cost. With a weight of 2.1 tons available on each machine for passengers and mails twenty passengers might be carried. To cover the working costs and interest they must be charged $575 per head. The rate for mails would be $5,500 per ton.