Copyright
Osborne Reynolds.

Papers on mechanical and physical subjects (Volume 1) online

. (page 39 of 40)
Online LibraryOsborne ReynoldsPapers on mechanical and physical subjects (Volume 1) → online text (page 39 of 40)
Font size
QR-code for this ebook


have resulted had the shot jammed when in full career and carried away the
fore part of the gun, or it might have resulted from the gradual weakening of
the section of the gun at the shoulder owing to the different degrees of
expansion immediately before and immediately behind. One or other of
these causes appeared to afford the most probable explanation of the phe-
nomena as described in the early accounts. In various subsequent reports,
however, it was stated that fragments of the fore part of the gun were blown
about in all directions. So that the gun, instead of having simply broken in
two, must have burst like a shell in front of the first shoulder. This fact
placed the phenomena in an altogether different light. The explosive
bursting of the zone of the gun into fragments implied an enormous excess
of pressure at this point of the gun.

In order to cause the tube of the gun to burst longitudinally at all would
require several times the normal pressure, and the breaking up of the wrought-
iron tube into fragments would show that the force was largely in excess of
what was necessary to burst it.

After seeing these reports it appeared certain that the gun had been
subjected, at the point of rupture, to a pressure enormously excessive, and
the question became, whence could such a pressure have arisen ? To me it
appeared that nothing short of such an action as might, with a detonating
fuse, result from the explosion of gun cotton or dynamite would explain the
breaking of the gun into fragments. Had the shot become jammed the
pressure might have been raised sufficiently to burst the gun, but with pebble
powder even this seemed doubtful, and such an action seemed altogether
inadequate to explain the breaking of the gun into fragments. It appeared,
therefore, that there was but one conclusion to be drawn there had been
something abnormal in the loading. Had the gun been loaded with small
grained powder, gun cotton, or dynamite, instead of pebble powder, such a
result might have been produced ; but then, the gun would, if it had burst,
have burst at the breach unless the shot had slipped forward, and that there
should have been two accidents appeared highly improbable. Besides, it was
necessary to consider what sort of a mistake was most likely to have occurred ;
and the only possible mistake that could have been made on the spot appeared
to be that of double loading.

The fact that if two complete charges were put into the gun, the powder
of the second charge would be directly beneath the point of rupture appeared
in favour of this, the easiest mistake. But would, supposing the powder to
have been pebble powder, the pressure from the two charges have been
sufficient to cause the result ? At first it seemed to me that even supposing



36] ON THE BURSTING OF THE GUN ON BOARD THE THUNDERER. 401

that the second charge had been ignited by the first, which was doubtful, this
would not explain the suddenness or magnitude of the pressure. But on
further consideration it appeared certain that the second charge would not be
ignited by the fire from the first ; and it then became clear that in this very
fact we should have an amply sufficient explanation of the excessive pressure.

My object in writing this paper is to point out the probability of this
explanation, and so, if possible, to induce the authorities to test it. It
occurred to me several days before the report of the Committee appeared,
and in spite of the improbability of such a mistake as double loading, I could
not shake off the conviction that it afforded the true explanation. As I have
pointed out, the blowing into fragments of a wrought-iron tube implied an
explosive action such as might result from gun cotton or dynamite but which
could not be produced by the slow burning of pebble powder. The point to
be explained then is how the second charge could be brought into such a
condition that it would explode like gun cotton. To understand this it must
be remembered that in the usual way the grains of gunpowder burn from
their outside only, so that the thicker the grains the longer will be the time
occupied in burning, and for the same weight of powder the slower will the
gas be given off. The reason why gun cotton is so much more destructive
than gunpowder is not that it gives off more gas weight for weight, but that
when ignited by a flash it burns so much quicker. If, therefore, by any means
the whole mass of gunpowder could be heated up to the firing point at the
same instant, so that the grains fired simultaneously inside as well as out, the
action of the powder would be as quick or quicker than the gun cotton. And
still further, if besides being heated the powder was compressed into a fraction
of the space it usually occupies, the gases so confined would be capable of a
still greater pressure.

Now if the after cartridge were fired and the forward cartridge were not
ignited by the flash, and considering the length and fit of the shot it could
hardly have been so ignited, then the after shot would be driven forward
closing on to the forward shot and compressing the powder between until the
pressure on the forward shot was at least half as great as the pressure of the
gases behind the after shot, which would be between 10 and 20 tons on the
square inch. Thus the powder would be subjected to a squeeze between the
two shot such as would result from a blow. It would be compressed to a
fraction of its former volume. The cubes would be crushed into a cake and
the work of compression would be sufficient to heat the powder far beyond its
point of ignition. Thus the entire mass of powder would be simultaneously
ignited in a highly compressed and heated state. The force of such an
explosion would be practically unlimited and would be located at the very
point at which the gun burst. Hence in such an action we have ample cause
for the effect produced.

o. E. 26



402 ON THE BURSTING OF THE GUN ON BOARD THE THUNDERER. [36

But it will be asked why does not the same thing happen when a rifle is
doubly loaded ? It is said that in that case the second cartridge is generally
blown out before it ignites, and this may be so, for in the rifle the pressure of
the gas on the shot can never exceed above a twentieth part of what it is in
the 1 2-inch gun, and hence in the case of the rifle its pressure may well be
insufficient to ignite the powder between the shot.

This view of the action resulting from the firing of powder by percussion
appears to me to be one which it would be well worth while to test, for if
proved it would completely re-establish confidence in the strength of the
guns, which has been somewhat rudely shaken.

Let a 1 2-inch gun be loaded with a double charge of powder and a double
charge of shot, or a shot of double weight, and fired. If, as is probable, the
gun does not burst, confidence in the gun will be re-established. Then let it
be loaded twice over with the powder between the shot so as to ascertain
whether the action of the powder when fired by percussion would not produce
an effect similar to that which we are here considering. The destruction of
one gun for the purpose of establishing confidence in all the rest would not
seem to be an unworthy sacrifice.



37.

ON THE STEERING OF SHIPS.
[From the "British Association Report," 1880.]

I HAVE received an important communication from the Admiralty, upon
the steering qualities and turning powers of H.M.S. ' Minotaur ' and ' Defence.'
As the experiments therein described were made in accordance with the
request of the Committee of the British Association upon the Steering of
Ships, and as the results obtained are very definite and important, I think
it desirable that they should be placed upon record. I therefore append
them to this notice. (See Tables, pp. 404 407.)



ADMIRALTY, S.W.,

19th September, 1879.

SIR,

I am commanded by my Lords Commissioners of the Admiralty
to forward to you, herewith, for your information, with reference to my letter
of the 30th April, 1877, S. f-^ff, the accompanying copy of a letter, dated the
31st July last, from Vice-Admiral Lord John Hay, commanding Channel
Squadron, enclosing a copy of the tabular statements, forwarded therein, of
the Trials .of the Steering Qualities and Turning Powers of H.M.S. ' Minotaur '
and ' Defence.'

I am, Sir, your obedient servant,

ROBERT HALL.

Osborne Reynolds, Esq.,
The Owens College, Manchester.

262



404



[37



TRIAL OF



H.M.S. 'DEFENCE,' off Syracuse, Feb. 14, 1879.

Tonnage, 3720. Length, 280 ft. Beam, 54 ft.

Fitted with Griffiths's two-bladed left-handed propeller.

Immersion, 6 ft. Draught of water forward, 25 ft.; aft, 26 ft.



No. of
Trial




Experi-
ments


Engines


Helm


Wind


corre-




in each








spond-
ing to
British


NATUEE OF TRIAL,


case to
be dis-
tinguish


Time requirec
to stop or


Direction and time


Force and direction


Associ-




ed by


reverse


required to place it there


relative to ship


ation




letters


(seconds)












Stop Rev'rse


Trns. Deg. Sec.






Ship goi ng full speed












ahead, the screw sud-










I.


denly reversed and


A


20 55


Port 3^ = 25 in 40


Light air




the helm put hard


B


15 55


3 = 25 ,,35


) Light




over.


C


14 54


3| = 25 ,, 25


air






D


15 57


3 =22 ,, 23


j ahead




The same repeated


A


14 38


Starbd.34 = 25in23


Calm.


II.


with helm set in op-


B


17 43


,, 3i = 25 ,, 28


\ 9 points from port




posite direction.


C


13 58


3| = 25,,28


j bow force 3




The ship going fast










III.


astern, the screw sud-
denly started to drive
her ahead and helm
put hard over as in


A
B
C


12 32
8 35
10 40


Port 3J = 25in25
3| = 25,,26
3| = 25 13


11 points) from port
11 V bow
7 \ force 3




Trial I.




















Points Bow force


TV


Trial III. repeated


A


15 42


Starbd.3*=25in20


2 from starbd. 3


XV.


with the helm in the


B


11 31


,, 3| = 25,,24


11 port 3




opposite direction.


C


13 38


3| = 25,,18


3 3




Ship going full speed


A






South.


V.


ahead with the helm






Amidships


1 to 2




amidships.


D






Starboard quarter






E












F












A










Ship going full speed


B








VI.


ahead, then the screw


C




Amidships


Calm. 1 o.




reversed with the helm


D










amidships.


E












F









37]



405



STEERING QUALITIES.



I. H. P., 1902-5.
Diameter, 18 ft.
Speed at trials, 8 knots.



Pitch, 21 ft.



(Maximum speed, 8'5 knots.
{Revolutions of engines, 63 per minute.
Revolutions of engines, 61 per minute.







RESULTS








Angle and direction


Time
taken


Time
ship's head


Time from
first order


Angle and direction of ship's


REMARKS


ship's head went first


going


returned


till way


head when way was stopped






ditto


to object


wasstopped






6f points starboard


Min. Sec.
2 20


Nil


Miu. Sec.
3 30


54 points starboard, from
time engines reversed to
way stopped head went to
port 1J points.


A. Helm put over
when engines were
stopped.

BP, T) rln rln


i ,, port
J , , starboard


55
1 45


Nil
Not timed


3 45
3 30


44 points port

5 ,, ,,


when engines were


1


1 50


Not timed


3 25


3J M M














Helm put over when


J point port


1 25


Nil


3 13


2| points port


engines went astern.


Very slowly to starbd.


2 12


Nil


2 12


i


do. do. do.


Gradually to port


3 38


Nil


3 38




wind springing up












force 3.












Helm put over when


Gradually
to
port


2 18
1 26
2 32


Nil
Nil
Nil


2 18
1 26
2 32


2| points port

24 ,,
3


engines went ahead.
NOTE. With helm
amidships the ship's
head swings to port












with stern way.


! Continually to port
j when going astern


2 20
1 55

1 57


Nil
Nil
Nil


2 20
1 55

1 57


5 points port

3} !,' ',!


Helm put over when
engines went ahead.




Minutes






X 1J points starb'd, from




X Y

Nil f pts. port
l^pts.stbd. l| stbd.
2 1*
2 1*

li 2


X Y
5 5

5 5
5 5
5 5
5 5


%


31 30


time engines stopped and
reversed to way stopped
head went to port 6 points.
Y 4| points starb'd from
time (as above) head went
to port 3 points in 3 min.


Ship going ahead
8 knots at commence-
ment of trial.
Y Time taken from
starting.


li Hi


o o






30 sec.






Minutes










74 points port
134
13|
14 ,>/

13 f /

1*4 / ,,


5
5
5
5
5
5


1st circle
14 minutes
2nd circle
11 minutes
30 seconds


32 30


89 J points port, viz. twice
round the compass to port
and 17^ points, from time
engines were stopped to
way stopped 4 points to
port in 2 min. 30 sec.


First time making
a complete circle in
14 minutes.
Second time 11
minutes 30 seconds.



(Signed)



R. R. CATOR, CAPTAIN.



a "





os .2 'a
85 *B H



J

a-



*9

C"

S o o



4



If 1.9-S



-

eg a)

i





T3 oo a

O* 03


g"














01 rd'S


5 * ^
















a s .












OS
M

3


. ^

OS* 60


|.?^1

rfl H> O










65

9
















ft
















-<


H

3


^^ .; "S

00 iH O 3


^rS gl 1










a






fi ^ 02 (p










JT:




jjj a 02 oj


O O O 'ft










o




H ,.~ <


M^_ a










02






O 3 O














" "^


6C 03










^




0-T3 *


P -s


a^=










PH




111 If


J8


jo s










W




C? g .&J= M


-*3 "^


.3 O

o HNQ










H




^1 fS """" ^


,S o t-


>; (M o










PH




?


^i (7<I CO


^i CO rH















iHii


g !> O CO
OjrH 5 (M


gO rH 10
OQCO (N CO










ffi




^Illf


= rH <M <M


|^WCq




























1-1


ESULT


.1 "& g g 5"


fi .

a goi<N

1-^ OQ CO "^


rj
OJ

K c8










3s

02


pq






d














23


o g^


S*! H














SS^S


gt t^ CO

QQ ^* IO CO


xoo o o

CO -*






a

'a :


Q
1






bo-0




grH rH rH






rH rH


rH






a, ill


;t-?l M-Tl

^CO t ^H


Q IO CO






t> rH


b






^Ifi


1 S ' S


g S

PH






1 =


B
o
PH








CO


















"2


g






'B rt


re







g^.2 >


a o


o a <B






SC3


g a a>




P


PJfl


"S *-"


-0 o3 S






111

J o


111








00


CO "






02


02








gCO OS rH


w CO t^- CO








00




|

"3


g gT3 a.


E

o - r


| E S






CO ..

13 '


ft

1






5!r?Ss


PH

Q; OS OS OS

^ CO CO CO


CQ

i-W-r^

j CQ CO CO
Q CO CO CO






a








"So.












c3




a
fi


Hfo*I


g t- CO CO


|S3S








o>

03

rH








..






e -


e




NATURE OF TRIAL


Ship going full speed
ahead, the screw sudden-
ly reversed and the helm
put hard over.


r^S QJ

S'^ fi
*> .2

B fj

M ^

S >5


The ship going fast
astern, the screw sudden-
ly started to drive her
ahead, and the helm put
hard over as in Trial I.


Trial III. repeated with
the helm in the opposite
direction.


OJ ^

s >

60 _a

'o '2 oo

to ** ft

03 03


O> m ^

III

^^ 03
fl* G '"S

.3 01 ^ .
O J2 03

tsC^S - g,

Qj ^ ^ _f]




o-jri.sl-ij.
















***|o|


I-H


HH
r 1


HH
rH




r*


>







REMARKS


ship in this case answers the re-
iffect of rudder and action of screw.

acts under reversed effect of rudder.

1 be seen that the ship goes 1^ times
3 port (due to screw) as in trial 5.


] d) r^
03 rg fl __

S CO * *'

(3n 03 O *

"** O

O -tT aj ^
? SH CO ""
-g h CO

* 4H ^1

'3 co O S

Q "- 1


|2

^ rt

1.9

O - JH

<n"S g




d

0)

_d

<D
CO

i

1

CO

CO

CD

03



CD CD


ese cases ship obeys the influence
reversed effect of rudder. These
of 3 and 4 show that the direction
ead may turn is uncertain.


<U 0) co 173
4343 S a
- -w d <u

w-y^

f^l'rfj

S"l
RIII

q-lll

^'I*o^

03 3 _ + q

a s ^^^

2 ^ ^ s r

g^s g a

P ^ CD

ll^l

JH ^ 60 03 CH


2 complete circles to port in
and 11^ min. respectively.


JOHN HAY, VICE -ADMIRAL.






^ n -

T3 .g< S n

2 S a*


liii


d 1^


11


B o CO-

(-] -^ CO

.B ^ s "ft

H- 1 m .rH


CO d Tj Q

s|s,r

H'S>2g<g


il
|1
















" CD 43


d o -w S










> eS


* . 03


SH 03


O


O SH CO


CD "4-1 CO !?


r-l


13

<o




r B


HJ


SH SH -if SH


"S IS


"S "S -


SH SH SH






d

_6D




O OJTH,


rt '^1-'-*^


g


o ~^ o





000










if i


PH -2^3






PH PH (lj


PnPn PH






O2




=3 "3


H

hn


-2-20-2


2 *" 03 -2


3 O


O O












HJ 60 o
* 43


-2 -2 > -2


en .3 J to


CO CO M


to 02 CO










"" *


cp 3 3


.S.S "a .9


.9 p, o3 .3


11-2


"q _ _d














'o 'o "g 'o






'o 'o 'o










Ifii {*'


rjjl TH "


a CH g, A


p < '-WO2 p^


PH ft PL,


PH ft ft










"Jo


GO -v
<N


H^HCTj- rHM<
T ( ^ CO


COW KU
CM r-l


J^^co


>O CN CO








B




O CO O O


O IO kO O
* >O O > 1
1 1 1 I I 1


5 <M 00
00 CO i-H
i i <N




1








n






.3 : :




B


*




d' .







O


d


"73 d _d


: d


1


"S d


"o-S


S's'
















o S


o> a








1


60
O>


43 'i'i


SH

_^v O


o


o 2


go


*O w
fl OJ










i3 3 O O










bo






SH
CC


<?3 . >rH


-" -^ 'S "S


' *" .3 o


03


(x, 60


S .








a




^ r S 5 ^


o -2 -2


o'^'S ">>


R

>a


ll


OJ Q.


E>






V








03


3 60




00 rf






K


<" Tt<


d ^ i ^ ^J


H-3 - H O "3


SH


d


^ H^


"* -








J CO CO W5


3.3.3.2


_d M 4^ D


O


'-3


I 1


i-H








;H * H-3 HJ

~ !H SH SH


P-, O O O


SH^ 5 ^




d
o












-S o o o








rt












02 PH PH PH


CO i lil'H'CCHi


^t ^
















SH


SH SH SH SH






SH SH SH








H-




03 _
















M


ja


O SH rj S


O O O


SH SH SH


SH SH SH


000


J"j


^H




H


a


43 !
SH p| i^ I^H


a a*a a


O O

PH PH PH


O O

PH PH PH


43 43 42
- SH SH SH
03 03 03

-*_> -*j -*->


*


&




O




02


O2 O2 O2 02






020202








&"*




60


SO


^












QO

US
H S5

1


a

.3


as d

ill

IP


CD q
3 '3 d

^i-n rt SH

S S s

43 q *

Sa3

K o


SH SH


Port
Port
Starboard


T3 T3

SH SH
03 .3 03
SH O
43 43

03^ a

4^ -f^

02 02


n3

SH jj
03 CO

43 cd

Jn

02


%




BflH

ss







6


PH P-i












B S5





ns






r^ r^ r^


^S -d 'd


*a






CO 1 " 1


"S


SH






SH SH SH


SH SH SH


SH






fetf

|o




"5 "S o "S

O O 43 o


""""
o o o o


SH SH SH
O O


o3 c3 o3
O
43 43 43


O O


03


s


SH

O






^s


PH PH S PH


PH PH PH PH


PH PH PH


o3 03 03


03 03 03


a


PH




o


s


02






02 O2 02


020202


02






H




M




t3 r^ r^j


r r^ r%3










o


d ^_






SH SH SH


SH SH SH














03




o3 o3 o3




_ t _ 3








5 /


/||1


" c8


513 "

O O

PH PH PH PH


O
43 43 43
SH SH SH

03 o3 03


O O O

43 43 43
SH SH SH

03 03 03


SH SH SH
O O

PH PH PH


g


B




/




02




O2 02 O2


020202










/ c


fl


^5-2


^3 -O Ci ^


e -o o


^o










H


1


e e
















d




~3


i 1 CN W5 CO




CM


CO


^


C


CO






H






















a






1


1










L


03






1












2


"o






<


1










n









i






1









408 ON THE STEERING OF SHIPS. [37

S. 8087. 1879.
STEERING QUALITIES AND TURNING POWERS OF SCREW SHIPS.

' Minotaur ' at Vigo,

31st July, 1879.

No. 165.

Sm,

With reference to your letter of the 25th April, 1877, S. ffff,
addressed to my predecessor, Vice-Admiral Sir Beauchamp P. Seymour,
relative to the Steering Qualities and Turning Powers of Screw Ships, I
have now the honour to enclose for the information of the Lords Com-
missioners of the Admiralty the results of experiments that have, under my
direction, taken place in H.M. Ships ' Minotaur ' and ' Defence,' together
with a summary of the same observing that these experiments so far as
they go, seem to be useful as illustrating the views of the British Association.

I have, &c.,

JOHN HAY,

Vice-Admiral Commanding.

To the Secretary of the Admiralty.



38.



ON THE EFFECT OF OIL IN DESTROYING WAVES ON
THE SURFACE OF WATER.

[From the " British Association Report," 1880.]

THIS paper contained a short account of an investigation from which it
appeared that the effect of oil on the surface of water to prevent wind-waves
and destroy waves already existing, was owing to the surface-tension of the
water over which the oil spread, varying inversely as the thickness of the
oil, thus introducing tangential stiffness into the oil-sheet, which prevented
the oil taking up the tangential motion of the water beneath. Several other
phenomena were also mentioned. The author hopes shortly to publish a full
account of the investigation.



39.

ON SURFACE-TENSION AND CAPILLARY ACTION.

[From the " British Association Report," 1881.]

IN the first place it was pointed out that, although surface-tension has
hitherto been considered as a statical or hydrostatical force only, such actions
as the spreading of oil upon water exhibit phenomena, and those of a very
marked kind, which depend, not on a statical force, but on the maintenance
of this force while the surface is contracting at a very high velocity. And,
in the second place, it was pointed out that the assumptions on which
Laplace's theory of surface-tension is founded are insufficient to explain
these phenomena, which suggest certain relations between the range of the
intermolecular attractive forces and the dimensions of these molecules.

It was shown that if the surface of pure water be touched at some point
with a slightly oiled needle, the oil spreads out quickly in a circular patch,
which patch at first extends with great rapidity. But it was not the rapidity
of extension that was so much the point of remark, as the motion of the
surface of the pure water before the advancing oil. In the usual way this
motion is shown by a rib or slight elevation of the water immediately at the
edge of the oil. When the initial surface is very clean the rib is always
formed, but it only becomes apparent under peculiar circumstances. It is
often apparent on the surface of a deep pool formed at a sharp bend of a
stream, for instance, to anyone fishing. The more rapid flow into the pool
causes ascending currents, which, spreading out at the surface, give rise to
radial currents of pure water, which sweep back and hold at bay the oil or
transparent scum on the surface of the rest of the pool, and which but for
the outward motion would rapidly extend over the pure surface. Under
these circumstances the edge of the scum is definitely marked by a fine rib,
which shows itself in certain lights as though a fine gut-line were floating on



39] ON SURFACE-TENSION AND CAPILLARY ACTION. 411

the water and were carried, first in one direction and then in the other,
according as the radial current or the spreading force of the scum is in the
ascendant. It is difficult to render this rib apparent on the surface of water
contained in a vessel, although this may be one or two feet in diameter.
This may be done, but the motion which gives rise to the rib may be
rendered apparent by other means, by dusting the surface of the pure water
with some insoluble powder such as flowers of sulphur. The motion of the
surface is rendered apparent by the motion of the dust. It is then seen that
the dust does not fall back before the oil as though the surface of the pure
water were in a general state of contraction, for there is absolutely no motion
in the dust except in the immediate neighbourhood of the edge of the oil. It
is as though the dust were swept back by the advancing edge of the oil ; the
dust, already swept up into a compact mass, coming up to each fresh particle,
pushes it before it, until a bright yellow band is formed marking the edge of
the oil. The result is to give the impression that the dust is being driven
back by the oil as if the oil were spreading from some inherent expansive
force ; but, as a matter of fact, the oil is being drawn forward by the con-
traction of the dust-covered surface of the pure water, and the fact that the



Online LibraryOsborne ReynoldsPapers on mechanical and physical subjects (Volume 1) → online text (page 39 of 40)