These formulae are based upon the assumption that the area of propeller disk should be proportional to the indicated horse power, divided by the cube of the speed, and the same with the projected area of the propeller and also the surface. TABLE IV. _Particulars of Propellers and Constants._ ------------------------------+-------+---------+----------+-------------- | Length| | Proj. | Feet per Ship. | of | Disk | surf. | minute. | ship. |constant.| constant.|Speed of tips. ------------------------------+-------+---------+----------+-------------- City of Rome. | 542 | 220 | 69 | 4,715 Normandie | 459 | 250 | 66 | 4,099 Furnessia | 445 | 223 | 69 | 3,654 Eden | 300 | 211 | 64 | 3,080 Yorouba | 270 | 213 | 63 | 3,202 Taygete | 260 | 238 | 56 | 3,166 Kow-shing | 250 | 171 | 69 | 3,369 S.Y. Monarch | 152 | 221 | 65 | 4,040 S.Y. Aries | 138 | 179 | 56 | 2,986 Twin screw Fenella | 200 | 244 | 64 | 2,890 Twin screw H.M.S. Fearless[2] | 220 | 277 | 67 | 5,022 Twin screw H.M.S. Iris | --- | 454[6]| 135[6] | --- Twin screw H.M.S. Iris [3] | 300 | 412 | 221 | --- Twin screw H.M.S. Iris [4] | 300 | 346 | 99 | 4,961 Twin screw H.M.S. Iris [5] | 300 | 439 | 82 | 5,309 ------------------------------+-------+---------+----------+------------- [Footnote 2: Estimated with a speed of 17.5 knots and 3,370 I.H.P.] [Footnote 3: With the first propeller at the estimated speed of 17.5 knots and 7,000 I.H.P.] [Footnote 4: With four bladed modified Griffith's on actual trial.] [Footnote 5: With two bladed modified Griffith's on actual trial.] [Footnote 6: Constants obtained from first propeller calculated from a speed of 18.5 knots and 7,500 I.H.P. Area of propeller disk x speed of ship in knots. cubed Disk constant = -------------------------------------------------- I.H.P. Projected Projected area of propeller x speed of ships in knots. cubed area = ------------------------------------------------------ of constants I.H.P. Expanded area constants may be obtained and used in the same way.]