310 MESSES. E. H. FOWLEE, E. G. GALLOP, C. N. H. LOCK AND H. W. EICHMOND: 
As already mentioned in § 1.1, the low velocity value of f L , as determined in the 
wind channel, is somewhat doubtful.* There appears to be a distinct minimum in 
this coefficient soon after the velocity of sound, followed by a steady rise. This type 
of curve is rather unexpected, and confirmation by a repetition of the experiment is 
very desirable. We may emphasise again that fjfa is by no means constant, and 
that (see fig. 15) undergoes considerable variations. 
1.22. The Force Components / H and Others. —We have now to exhibit the information 
obtainable from the damping of the oscillations of the axis. When f h is known, 
this information (see § 4.12), provides numerical values for two quantities, one of 
which is / H and the other j R + e, where e depends on the coefficients and f x and is 
a priori unlikely to be comparable with f n . The data at our disposal are very rough 
and could be improved on in future experiments. The present results vary largely in 
some cases from round to round ; the value of e is much larger than its expected value 
and of the opposite sign. The general features of the damping (see figs. 12, 14) 
are however clear and qualitatively consistent. We can assert that the following rough 
values of/ H , given in Table II., are of the right order of magnitude and perhaps not 
in error by more than 50 per cent. Owing to their roughness they are given for the 
groups as fired. An attempt has been made to determine f R in a wind channel at 
low velocities, the value 22 being obtained. 
Table II.—Probable Values of jf H , the Coefficient of the Yawing Moment due to Yawing. 
Groups I., II., III. refer to shells of Form A with various positions of the centre of 
gravity (see § 2.2). Group IV. refers to Form B. 
Group. 
Muzzle velocity. 
/h- 
Group. 
Muzzle velocity. 
/h- 
Group. 
Muzzle velocity. 
u 
I. 22-24 
1119 
80 
II. 24 
1292 
70 
III. 1-4 
2025 
70 
I. 25, 26 
1326 
70 
II. 5-7 
22, 23t 
1587 
75 
IV. 13-15 
1078 
55 
I. 27, 28 
1563 
60 
II. 1-4 
2024 
60 
IV. 16-18 
1547 
75 
I. 1-4 
2167 
35 
III. 17-19 
1119 
40 
IV. 24-26 
2120 
80 
I. 19-21 
2320 
30 
III. 20,21 
1292 
70 
II. 17-19 
1119 
90 
III. 22, 23 
1567 
60 
* In fig. 4, and subsequently, the low velocity value of / L is assumed to be / L (10°) in place 
of Lt / L (8), whieb is uncertain. 
t From guns of different riflings, with results in agreement. 
