ON STEAM-SHIP PERFORMANCE. 63 



4. Groups that are very numerous to be divided iuto subgroups, according 

 to displacement, viz. : — 



Subgroup A, below 125 tons 



„ B, from 125 to 250 tons 



5. Eesults of trials at low speedtJ, or " half-boUer power," to be placed in 

 the group proper to the speed. 



6. In the following plan for the arrangement of a Table, each vessel of a 

 group or subgroup occupies a column, and the several data for each vessel 

 appear in a series of lines. The data consist of twelve essential items 

 marked E (without which no vessel should be admitted) and twenty others, 

 making thirty-two in all ; so that octavo pages will hold the Tables. 



7. Where trials of performance under sail have been recorded, supple- 

 mentary Tables may be added. 



Arrangement of Table for a given group or subgroup. 



Group No , speed between .... and .... knots. 



Subgroup No , displacement between .... and .... tons. 



1. E. Name of vessel (or reference number) I I I • 



Vessel. 



2. E. Length on loadwater-line, in feet. 



3. „ of fore-body (marked F. in tables). 



4. „ middle-body (marked M. in tables). 



5. „ after-body (marked A. in tables). 

 G. E. Breadth, extreme immersed, in feet. 



7. E. Dej^th of immersio i, mean, in fee^. 



8. Immersed midship section in square feet. 



9. E. Displacement, tons of 35 cubic feet. 



10. Mean immersed girth, feet (from actual measurement, and not other- 



wise) . 



11. Material and state of skin. 



12. Coefficient of fineness of waterlines= displacement -^(L x 0). 



Propeliee. 



13. E. Description (paddle, common or feathering : screw, Smith's, "Wood- 

 ci-ott's, Mangin's, Griffith's, (tc. : jet propeller). 



14. E. Diameter (for common paddles, to outer edge ; for feathering 

 paddles, to joiu-nals ; for screw, to tips of blades), in feet. 



15. Number of blades or paddles. 



16. E. Pitch of screw (if not uniform, state extreme and mean pitches), 

 in feet. 



17. Aggregate mean length of screw-blades (along axis). 



18. Immersion (of upper and lower edges of paddle or screw), in feet. 



