114 REPORT—1843. 
The methods of drawing these vessels through the water varied with the 
scale on which the experiments were made. ‘Those on the smallest scale 
were drawn by a weight arranged in such a manner as to supply a uniform 
force through any given distance. Those ona larger scale combined the 
power of horses with the action of a weight, so as to apply their force, when 
freed from irregularities, to the same object. On a still larger scale the power 
of steam was employed, and on the largest scale the experiments were made 
on the sea by means of powerful towing vessels, In this way the experiments 
were made on a wide range of magnitude, both as regarded the vessels them- 
selves and the sheet of water on which they were propelled—an element of 
resistance not always sufficiently taken into account. 
The resistance was accurately measured by dynamometrie apparatus of 
great accuracy, through which the moving force was communicated to the 
vessel; the velocity being determined in certain cases by a peculiar appa- 
ratus designed for this purpose, and in other cases by instruments for mea- 
suring and marking time with accuracy. The observations were registered 
by independent observers ; carefully recorded by individuals employed for 
that purpose; then finally passed through a series of operations of reduc- 
tion so as to fit them for immediate reference and use in caleulation. After 
this process had been gone through by independent calculators, and not till 
then, were they made the subject of special examination with reference to 
every theory, and thus it was conceived that the greatest amount of authen- 
ticity had been secured. 
The author then proceeded to give to the Meeting a number of specimens 
of the results which the experiments afforded, such as he knew were likely to 
interest those members of the Section who were acquainted with the prinei- 
ples of naval construction. He demonstrated a remarkable law by which it 
appears that each velocity has a corresponding form and dimension peculiar 
to that velocity ; and he showed in a variety of diagrams the means of con- 
structing such forms. To show how much influence form alone, without an 
other element or dimension, affects the question of resistance, he adduced the 
following as one of the most important experiments. Four vessels were taken, 
having all the same length, the same breadth, the same depth, the same area 
and form of midship section, and all loaded to the same weight, displacement 
and draft of water, the only difference being in the character of the water- 
lines; No. I., being of the new form indicated by these experiments as that 
of least resistance; No. III., the old form, very nearly the reverse of the first; 
No. LI., intermediate between them; and No. IV. intermediate between No. I. 
and No. II. The following table shows the result of the comparative trial :— 
| Resistance | Resistance | Resistance | Resistance 
Speed in Miles per hour.| in pounds. |in pounds. | in pounds. | in pounds. 

—————_— 









No. I. | No. II. | No.1I.| 0. 1V. 

3 miles 10 12 12 dil 
4. 18 22 ZGinch mvrgis 
Lee a 28 38 AQ 35° 
6 — 39 ae 72 56° 
7— 52 96 129 84° 
I 

These differences showed how much might be gained, everything else being 
equal, by the adoption simply of judicious forms in the construction of the 

