EXPERIMENTS ON THE FROUDE. 105 
The hubs of the propellers were not changed after the blades were cut 
down so that the blades with small area-ratio had somewhat more clearance 
from the fair-water. 
In addition the propellers were all tried with their hubs set about 12 
inches abaft the fair-water. 
The results of the tests with these propellers are all shown by Figs. 
16 to 21, Plate, 47-52, which give the revolution, thrust and the shaft 
horse-power plotted on speeds. 
All the runs were made early in the morning to obtain favorable 
weather conditions; for some of the runs there was no appreciable move- 
TABLE III. PROPELLERS USED IN IQII. 
Type. Pitch, feet.| Sfearatio. | hub, inches, 
INOi Fieri e crete wtels arts wees 2.2 0.61 5.74 
Ue Wdéalotennic aoe 2.2 0.50 5.74 
Wino Adsodebosoasue 2.2 0.44 5-74 
ji CONE operon creer 2.2 0.36* 5-74 
INOS een ce eta oa 3.0 0.59 7.83 
CaS pcepe OOO ACORE 3.0 0.52* 7.83 
UB peieictceel soe cions ae 3.0 0.45 7.83 
INOMGI Siete mies sisters 3 1.6 0.60* 4.18 
Te eh te aaa RI 1.6 | 0.53 4.18 
BB iieccrsye ashes 1.6 0.44 4.18 
*A pproximate. 
ment of the air; during none of them was there more than a gentle 
breeze; nevertheless runs were made in both directions and lettered with 
and against the wind. The divergence of curves with and against the wind 
was in all cases small; the difference in revolutions or thrust was divided 
into thirds and one-third was added to the reading lettered with the wind. 
In Figs. 16 to 21, Plates 47-52, the mean curves only are shown. It is 
proper to say that the curves with and against the wind in every case were 
fair and passed through all the observed points. 
A certain discrepancy may be observed in Fig. 18, Plate 49, for which 
the curve for the original width of blade appears to be too low throughout. 
There is reason to consider that the propeller in that case was set about 
