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I/a;
MABINE
PEOPELLEES.
MAEINE
PEOPELLEES.
SYDNEY Wf BARNABY,
TlUnn EDJTinN. ■
E. & R N. SPON, 125, STKAND, LONDON.
NKW YORK: 12, COllTLANDT STBEET.
1891.
PREFACE
TO THIRD EDITION.
In issuing a third edition of this book it appeared
advisable to reconstruct and enlarge it in order to
introduce new material which had become avail-
able. The original form of lectures as delivered
to a class of students has been abandoned and the
book rewritten and brought up to date.
No attempt has been made to give a historical
review of marine propulsion, and of the innumer-
able forms of screw proposed since 1836, only
those are described which embody some intelligent
idea.
The table of constants for disc-area and revolu-
tions on p. 73 will, I think, be appreciated by those
who have many screws to design. The complete
series of model experiments upon which it is based
is the work of Mr. R. E. Froude, and I am indebted
to him for permission to make use of it.
There are many ways in which it is possible to
tabulate experimental results, but after much con-
sideration I believe that the table of constants
which I have here given is the best that can be
VI PREFACE TO THIRD EDITION.
devised, being independent of scale and equally
accurate for all sizes of propellers. It is possible
by means of it to design a screw which shall have
maximum efiBciency under any given conditions of
indicated horsepower and speed ; or if revolutions
or diameter are so limited as to preclude the adop-
tion of the most suitable dimensions, those may be
selected which will be the best under the given
conditions and the efficiency at once ascertained,
provided only that the vessel is of such a form that
the propulsive coefficient is not abnormal, and that
the designer can correctly estimate the speed of
the following current in which the screw works.
More than this I do not think can be reasonably
expected. No table can supply the place of judg-
ment and experience.
Sydney W. Barxaby.
The Hollies, Chiswick Mall, W.
September Uth, 1891.
PREFACE
TO FIRST EDITION.
In preparing these lectures for the students of the
Royal Naval College, I availed myself of informa-
tion from various sources.
Now that they are published verbatim in book
form, it becomes a duty as well as a pleasure to
acknowledge the assistance thus received.
I am indebted first of all — and who that studies
the subject of Marine Propulsion is not? — to
Professor Rankine. Also to Mr. W. Froude, Mr.
Bourne, Mr. White, Professor Osborne Reynolds,
Mr. Sennett, Mr. Maginnis, and Mr. Seaton.
There is, however, much that is new.
The curves in Plate II., which enable the dia-
meter, pitch, and speed of revolution of a screw
suitable for any horsepower and any speed to be
determined, are now made public for the first
time.
For most of the new material, and especially for
permission to publish these curves, and the method
of producing them, I am indebted to Mr. Thorny-
croft.
vm PREFACE TO FIRST EDITION.
It was my privilege to be associated with him
in making some 550 experiments with model
screws, and a (Considerable portion of these lectures
is the result of knowledge thus obtained.
I feel some diflBdence in putting forward in my
own name information so acquired, as the credit of
it is entirely due to Mr. Thornycroft, but after this
explanation, any merit which may be found in the
following pages will be attributed to the proper
source.
Sydney W. Barnaby.
The Hollies, Chiswiok Mall, W.
October 12/A, 1885.
PREFACE
TO SECOND EDITION.
I HAVE purposely adhered to the original form
of these lectures in preparing a second edition,
although they are not so well arranged as they
might have been, had they been written with a
view to future publication.
With the exception of such textual corrections
as were necessary, by reason of errors which had
been overlooked in the first edition, they remain
as they were delivered, and are largely supple-
mented by Notes in an Appendix.
I have to thank several correspondents who
have pointed out some of these errors, and I shall
be glad to be informed of any remaining un-
corrected.
I am especially indebted to Mr. C. H. Wingfield,
Assoc. M. Inst. C.E., for his careful revision of the
new edition.
Sydney W. Barnaby.
The Hollies, Chiswick Mall, W.
January lOth, 1887.
CONTENTS.
PAGB
CHAPTER I.
First Puinoiples .. .. .. .. 1
CHAPTER II.
The Paddle- wheel .. 6
CHAPTEE m.
.1. HE oOHE W •• •• •• at •• x^
CHAPTER IV.
Experiments with Models and their Applioatton to
THE Determination of the most suitable Dim en-
BIONS •• •* t. •• .• •• OJL
CHAPTER V.
Geometry of the Screw .. .. 75
CHAPTER VI.
The Htdraulio Propeller .. .. .. .. 94
CHAPTER VIL
The Sorew-turbine Propeller .. .. .. ..105
XNDKlk .. .• .• •• <* «• «( XXX
MARINE PROPELLERS.
^CHAPTER I.
FIRST PRINCIPLK8.
irly all marine pro-
of a mass of water
it of the required
f water acted upon
' second = W, and
ot per second im-
1 water = S, tlien
lie propelling force
is — . I" second : and this
is independent of the form ui ^ /opelling apparatus
altogether. S is commonly known as the real
slip, but will here be generally referred to as the
rate of acceleration, or more shortly •'is the accele-
ration.
When the vessel is in motion at a regular
WS
speed the reaction — is equal to the resistance.
B
MARINE PROPELLERS.
CHAPTER I.
ERRATUM.
Page ly, line 16, for "PR" read "PR -V."
18 where ^ = 32*2 feet per second; and this
%/
is independent of the form of propelling apparatus
altogether. S is commonly known as the real
slip, but will here be generally referred to as the
rate of acceleration, or more shortly as the accele-
ration.
When the vessel is in motion at a regular
WS
speed the reaction ig equal to the resistance.
B
MAEINE PEOPELLERS.
CHAPTER I.
FIRST PRINCIPLES.
The principle upon which nearly all marine pro-
pellers work is the projection of a mass of water
in a direction opposite to that of the required
motion of the vessel.
If the weight of the mass of water acted upon
by the propeller in pounds per second = W, and
if the sternward velocity in feet per second im-
parted to it in relation to still water = S, then
the reaction which constitutes the propelling force
is where ^ = 32*2 feet per second; and this
is independent of the form of propelling apparatus
altogether. S is commonly known as the real
slip, but will here be generally referred to as the
rate of acceleration, or more shortly as the accele-
ration.
When the vessel is in motion at a regular
WS
speed the reaction is equal to the resistance.
B
,V • V
2 MARINE PROPELLERS,
So long as there is a resistance to be overcome by
the propeller, there is no possibility of reducing
the real slip or acceleration S to zero, except
by making W, the weight of water acted upon,
infinite.
When a propeller is to be designed for any
given set of conditions, it is of the first importance
that the relation between the mass of water acted
upon and the acceleration imparted to it should be
WS
such that while the product — = — shall equal the
estimated resistance of the ship, and the size and
rate of motion of the propelling apparatus such
as shall suit the conditions of the case, the
economic result may yet be the best attainable,
or may only fall short of the maximum by an
£fcViqunt which is calculable^ and which it may
be desirable to sacrifice in order to obtain other
advantages.
The method of calculating the propulsive eflfect
of the screw from the backward slip is that
adopted by Rankine. Professor Greenhill has
published some able papers on the theory of the
screw,* in which he determines the propulsive
effect as due to the reaction of the water to the
rotatory motion given to it in the wake, and
Professor FitzGerald has shown f that if the
motion imparted to the water by a particular
* Trans. Inst. Naval Architects^ xxix. p. 819.
t Engineer^ August 22 and September 19, 1890.
FIR8T PRINCIPLES, 3
screw is assumed to be a certain form of vortex,
and a calculation be made of the power absorbed
in producing such a vortex, it will be found to
agree very well with the actual horsepower put
through the screw. It is to be hoped that light
will be thrown upon some remaining obscurities
in the action of the screw by these independent
investigations, but as they lead to the same con-
clusions as the older treatment, and as the latter is
simpler and of more general application, it has
been thought best to adhere to it.
Rankine has defined * the theoretical limit
towards which the efficiency of propellers may be
made to approximate by mechanical improvements,
and has pointed out certain causes which make
the actual efficiency fall short of that limit. He
states that " if the propelling instrument be so
constructed as to act upon each particle of water
at first with a velocity equal to the velocity of
feed " — that is the speed of the water entering the
propeller — '' and gradually increasing at a uniform
rate up to the velocity of discharge, then the loss
of work is the least possible." The oar, when a
uniform force is applied to it by the oarsman
throughout the stroke, approaches closely to this
limit, as does also the screw-turbine propeller.
(See p. 108.) .
There is a certain quantity of work which
* Engineer, 1867, xxiii. p. 25 ; and * Miscollanoons Scieutifio
Papers,' edited by W. G. Miller, p. 54.4. ^
B 2
4 MARINE PR0PELLEB8.
must be lost under all circumstances, and it is
equal to the actual energy of the discharged water
moving astern with a velocity S relative to still
water. As this energy varies as the weight
multiplied by the square of the velocity, if the
quantity of water acted upon is doubled the loss
from this cause is doubled, but if the acceleration
is doubled the loss is increased fourfold. This
explains why the hydraulic propeller, which is
forced to act upon a much less area of column
than the screw, appears at such a disadvantage
when compared with it.
The causes of loss of work in propellers of
diflferent kinds may be thus summed up: — 1st,
Suddenness of change from velocity of feed to
velocity of discharge. The radial paddle-wheel
is defective in this respect. The feathering wheel,
the screw, the Ruthven pump, and the oar are
more or less exempt. 2nd, Transverse motion
impressed on the water. Propellers which lose
in efiBciency from this cause are ordinary screws,
which impart rotary motion ; radial wheels, which
give both downward and upward motion in
entering and leaving the water ; and oars, which
impart outward and inward motion at the com-
mencement and end of the stroke respectively.
This loss is greatly reduced in the screw-turbine,
and may be entirely avoided in the hydraulic
propeller.. 3rd, Waste of energy of the feed
water. This is experienced by the hydraulic
FIRST PRINCIPLES.
propeller only as generally applied, and has been
one of the causes of its ineflSciency. It is not,
however, a defect inherent to it, and has been
avoided in some later applications.
6 MAEINE PROPELLERS,
CHAPTER II.
THE PADDLE-WHEEL.
As a propelling instrument the paddle-wheel
is not inferior to the screw, but its speed of
revolution is necessarily slow, and paddle engines
are therefore larger, costlier, and heavier than
screw engines of the same power. Until the
introduction of the screw-turbine, it was the only
propeller used for vessels of very shallow draught.
In order to ascertain the comparative value of
the paddle and screw for towing purposes, H.M.S.
Rattler and Alecto, the former a screw and the
latter a paddle vessel of the same size and power,
were lashed stem to stern. The Battler towed
the Alecto astern against the whole power of
her engines at the rate of 2*8 knots per hour.
Almost as much power can be developed with the
screw when the vessel is towing as when she is
running free, but this is not the case with the
paddle-wheel. The engines of the Alecto could
not get away, and were only able to develop 140
I.H.P., while the Battler was developing 300.
It is difficult to frame rules for determining
the proper area of floats for a given I.H.P. and
speed of vessel, because so much depends upon
THE PADDLE-WHEEL. 7
the position of the water surface in relation to the
wheel when the vessel is at full speed.
There is usually a wave hollow in way of the
wheel due to the motion of the vessel, and the
action of the paddles is to cause the water to run
towards them, and to produce a still greater de-
pression of level in front of and below the wheel.
Unless the vertical position is properly arranged
the immersion of the floats will be insuflBcient at
fiiU speed, and the slip will be excessive. It is
the practice of at least one eminent firm of ship-
builders to make model experiments in a tank,
with the wheel in place, and revolved by clock-
work at the proper speed, in order to ascertain
the amount of the depression. The usual course
followed in designing the wheels for a new vessel
is to work from the nearest type, within the builder's
experience, which has given good results.
Rankine gives a method of calculating the
effective sectional area of a pair of feathering
floats, which depends upon the general proposition
already stated (p. 1), and which is common to all
propellers.
If V = speed of vessel in feet per second ;
* S = speed of centre of float relatively to
the water in feet per second ;
A = area of a pair of floats in square feet ;
R = resistance of the vessel in pounds.
. s - — i-O^I— - V
100 - % of Blip
8 MARINE PROPELLERS,
W8
Then, since R = (see p. 1),
if
_ 64 xA(V -1.8)8
32
.•.A= «
2 ( V -h S) S
The formula is useful for purposes of com-
parison, as showing how the eflfective area varies
with power, speed, and slip, and it should give a
fair approximation to the area of float immersed
at full speed ; but as it is usual to make the top
edge of the lowest float about awash when the
vessel is at rest, the width will be increased above
that theoretically necessary by an amount equal to
the fall of water-level at the wheel.
In applying this formula to radial wheels, S
should be taken as the speed of the lower edge of
the float.
In radial wheels the number of floats should
equal the number of feet in diameter, and the
breadth of a float is usually from f inch to one
inch for each foot of diameter. In a feathering
wheel the floats should be half as numerous and
twice as broad as the floats of a radial wheel.
The width of the wheel should be from one-third
to one-half the breadth of the ship.
The diameter of the wheel is determined by
the intended speed of the ship, the slip, and the
number of revolutions considered most suitable,
THE PADDLE-WHEEL.
9
>f
yy
91
generally from 20 to 30 per minute, but some-
times as many as 50.
Example : —
Speed of ship 15 knots = say 1500 ft per minute.
Slip 16 per cent. = say 800
.-. Circumferential velocity of wheel = 1800
Reyolutions 80 per minute.
Diameter = rr-m t^z =19 feet.
3'14 X 80
The diameter would be taken at the centre of
floats in a feathering wheel.
Fifteen to twenty per cent, is an average slip.
The floats of a feathering wheel are constructed
to cleave the water without shock. If a, Fig. 1,
Pio. 1.
represents the direction of motion of a descending
float, and the distance moved through by it in a
given time if the vessel were stationary, and b
equals the travel of the ship in the same time, then
the actual path of the float is represented by the
MARINE PnOPELLERS.
THE PADDLE-WHEEL, 11
resultant. The plane of the float entering the
water should coincide with this line. It is found
that if a circle B F D, Fig. 2, be drawn through
the centres of the floats, lines from the summit F
to the points of intersection with the water-line B D
will generally give the direction of the floats with
sufficient accuracy. Levers, the lengths of which
are about three-fifths of the depth of the float, are
fixed perpendicularly at their centres B6, C(?, Drf.
The centre of a circle, in the circumference of
which the ends bed of these three levers lie, is
the centre of the excentric wbicb produces the
required motion of the floats. Fig. 3 represents
the wheels of a vessel built by Messrs. Napier,
Shanks, and Bell, and engined by Messrs. Rankin
and Blackmore, of Grreenock, to whom we are
indebted for the illustration. The dimensions of
the vessel are: — length, 260 feet; beam, 28 feet;
draught, 5 feet 9 inches. The I.H.R was 2680,
and the speed 18 i knots. The diameter of the
wheel is 20 feet 6 inches over the floats, which are
made of straight elm 9 feet 9 inches by 3 feet 6
inches. The revolutions were 47 per minute, and
the slip 26^ per cent. The lowest float was im-
mersed one inch from the top edge when at rest.
The slip is rather high, and it is probable that a
still better performance would have been obtained
if the wheel had been rather more immersed.
12
MARINE PROPELLERS.
CHAPTER III.
THE SCREW.
Three strings wound spirally round a cylinder
make a three-threaded screw. If instead of strings
flat blades be wound edgewise, each having an
edge soldered to the cylinder, then if a slice be cut
off as shown in Fig. 4, there will be one piece of
Fig. 4.
blade attached to the slice if the screw have one
thread, two pieces if two threads, and so on.
The "length of the blade" is equal to the
length of the slice thus cut off, and the length of
the cylinder necessary to contain one complete
convolution of the blade is the " pitch " of the
screw. The ratio of the length of the blade to
the pitch is called the " fraction of pitch," a term
more in use on the Continent than in this country.
It will be seen that the '' pitch " of the screw
has to do only with the form of the helix itself.
THE SCREW.
13
and has nothing to do with the velocity which
may be imparted by it to the water. Theoretically,
the blade is supposed to be of the form of a thin
plate, as shown in Pig. 4, of equal thickness
throughout and with both faces alike. The side
of the blade which presses against the water when
propelling the vessel ahead is called the " front "
or " driving face " ; the opposite side is the " back "
of the blade. When speaking of the screw as a
whole the nomenclature is commonly reversed,
"in front of the propeller" standing for forward
of the screw in relation to its position on the
vessel, and " behind the propeller " meaning abaft
it. These terms " in front " and ** behind," which
are apt to be confusing, will be avoided in this
work.
Fig. 5.
Fig. 5 shows a screw of " expanding or '' in-
creasing " pitch as originally proposed by Wood-
croft. The length of cylinder necessary to contain
14 MAEINE PR0PELLEB8.
a complete convolution is not the same at all
parts, and the pitch therefore is " variable." The
first turn of the thread has a pitch equal to the
length a b ; the second has a louger pitch equal
to 6e. If a slice be cut off the cylinder (repre-
sented in Fig. 5 by the screw-shaft) midway
between a and 6, and of any length, it would be
said to have a mean pitch equal io ah, A slice
taken at a position midway between b and c
would be said to have a mean pitch equal to 6 (?,
and similarly for any other part.
The edge of the blade which first meets the
water is called the " forward " or " leading " edge,
distinguishing it from the " after " or " trailing "
edge.
The *' disc area '' is the a^ea of the circle swept
by the blade tips.*
The " developed area " or " blade surface " is
the sum of the areas of all the blades, exclusive of
the boss.
The *' projected blade area " is the sum of the
areas of the blades, exclusive of the boss, pro-
jected upon an athwartship plane.
(It is convenient to use a term expressing the
relation which the product of the pitch and revo-
lutions of the screw per minute bears to the ad-
vance of the vessel through the water per minute.
This term is *' apparent slip."
* Eankine uses '* effective disc area," which is the area
exclofiiye of the area of the boss, but it is now usual to measure
disc area as defined in the text.
TEE SCREW, 15
If P = mean pitch ;
R = revolutions per minute ;
V = speed of ship in feet per minute ;
PR — Y
then — ^^D~^ X 100 = percentage of apparent
P R
slip. In the great majority of cases P R is greater
than V, but it is occasionally equal to or less than
V. The apparent slip is positive, nil, and negative
in the three cases respectively. The real slip or
acceleration of the water S (see p. 1) is not measur-
able from the pitch and revolutions of the screw.
A propeller placed at the stern of a vessel is in a
current having a forward mean velocity IT rftlativft
to still water caused by the friction of the skin of
the vessel. While the vessel advances at a velo-
city Y through the water, the ^^rew g^(^yftT]( ^ftg at a
less velocity = Y — U. If the apparent slip is nil
then the real slip of the screw is equal to U. Con-
ceive a propeller of increasing pitch which shall
be so designed that the pitch of the forward edge
multiplied by the revolutions per minute shall
be equal to the speed of the propeller through
tlie water, that is Y — U, and the pitch of the
after edge multiplied by the revolutions equal
to Y, then the mean pitch, as already ex-
plained, would be called 1- :. The late
Mr. Froude showed that under these circumstances
apparent negative slip is possible. He describes
an ideal case in which the whole of the resistance
16 MARINE PROPELLERS,
of a vessel consists in skin friction, wave-making
and other factors being excluded. The dynamic
equivalent of the propulsive force employed in
keeping her in motion is found in the frictional
wake, and a propeller which should pervadingly
operate upon the wake in such a manner as to
bring it gradually to rest, would, in thus neutralising
it, maintain the propulsive fprce, and, given esta-
blished motion, a theoretically perfect propeller,
quite clear of the ship's stern, would maintain that
motion and exhibit apparent negative slip equal to
half the forward mean velocity of the wake at the
point where the propeller operated.
In this case it is clear that apparent negative
slip results from the fact that while a sternward
velocity is supposed to be imparted to the water
equal to the product of the number of revolutions
multiplied by the pitch of the after edge of the
screw, the mean pitch of the screw itself is nomi-
nally less than the pitch of the after edge. Nega-
tive slip would disappear in this particular case if
the speed of advance of the screw were calculated
from the after pitch instead of from the mean.
Apparent negative slip is sometimes exhibited
by screws of uniform pitch when the ratio of
pitch to diameter is small. The twin screws of
H.M.S. Colling icoody with a pitch-ratio of 1*6,
gave 1 ' 26 per cent, apparent negative slip, and
this was increased to 2*56 per cent, when the
pitch-ratio was reduced to 1.
Tiii^: sciiEW. 17
Numerous explanations have been given of the
phenomenon of apparent negative sh'p, but none of
them can be accepted as satisfactorily accounting
for its occurrence in the case of well-formed uni-
form-pitch screws, the pitch of which has been
carefully verified as in the case of the Collingwood.
It has been suggested that the blades twist or
spring under the pressure of the water, which
would have the effect of increasing the pitch, and
that they recover their shape when the pressure is
relieved, so that measurements taken after the trial
even would be misleading.
If this were the case screws with thin blades
would be most likely to show negative slip,
but it is, on the contrary, generally met with
in screws with very thick blades where springing
would be least likely to occur. Moreover, it
might be expected that the metal would soon give
way by fatigue if it were distorted by the pres-
sure, as the fluctuations are very great and very
rapid.
What has been said about the effect of thick
blades lends force to another suggestion, which is
that it may be attributed to the effect of the round
back of the blades. It has been explained, p. 13,
that pitch is measured on the assumption that both
sides of a blade are alike. The effect of the round
back of the blade must be to increase the effective
pitch and to tend to reduce the apparent slip,
although it is difficult to say by how much, and it
c
18 ' MARINE PROPELLERS.
is not, in the author's opinion, sufficient to account
for the CoUingwood results.
It has been pointed out that the iatermittent
action of the blades passing through the dead water
abaft the stern-post of a full formed ship reduces
apparent slip and may even cause it to change
sign, but this does not afiFect the case of the ship
referred to, which is a fine ship, and the screws
being twin, are not behind a stern-post.
Another suggestion has been that the motion of
the particles in the wave which followed and enve-
loped the stem of the ship might produce apparent
negative slip. All attempted explanations based
upon the effect of dead water and following current
alone, apply only to a screw of increasing pitch,
and this has already been dealt with (p. 16).
They are quite inapplicable to a screw of uniform
pitch, and the same thing is true of the theory
based upon the circular motion of the particles of
water in waves. The waves referred to are pre-
sumably those made by the vessel, because it can-
not be contended that negative slip results from
the screw working among free waves. It is well
known that the contrary effect is produced, the
slip is increased, and the most favourable condition
for the exhibition of apparent negative slip is still
water. If a wave follows the ship, and its energy
can be made use of in any way by the screw, that
wave has previously been created by the ship from
which the energy has been robbed, and can be only
THE SCREW. 19
partially restored. Could it all be given back, and
could the whole of the energy of the frictional wake
be utilised by the screw without loss, there would
still be no surplus thrust to keep the vessel in
motion. It is certain that there must be a stream
of water left behind by the screw having stemward
motion relative to still water. How is it then that
notwithstanding this necessity, apparent negative
slip is occasionally obtained with screws of uniform
pitch ? In a paper read before the Institution of
Civil Engineers on the screw propeller,* the author
gave what seems to him a satisfactory explanation
based upon a proposition recently enunciated by
Mr. R. E. Froude,f to the effect that the slip or
acceleration S of the water in the race was always
in excess of the slip of the screw [P R: vMr. Froude
showed that if no rotation were produced in the
race by the propeller, a limiting case was reached
in which one-half of the whole acceleration would
be produced forward of the propeller and one-half
aft of it. The water forward of the propeller was
aflfected before it was actually in contact with it,
and would run towards the screw, meeting it with
g
a velocity, as regards still water, of o, and the
action of the propeller upon the water while in
* * Proceedings of the InBtitution of Civil Engineers,' cii.
p. 74.
t * Transactions of the Institution of Naval Architects/ 1889,
p. 390.
C 2
20 MARINE PBOPELLERS,
contact was to accumulate pressure which had the
effect of increasing the acceleration of the race
after it had left the propeller. This is perhaps
more easily understood if we suppose the propeller
to be stationary in an ocean moving with a velocity
V. At some distance forward of the propeller the
water will be advancing to meet it at a velocity V.
On nearing the propeller, the water is accelerated
by its sucking action, and meets it at a velocity
S
V + -5. The length of the blades may be supposed
to be so small that no appreciable change in velo-
city can take place in the stream while actually
passing through them, but after leaving them the
speed of the stream is further accelerated up to the
final speed Y + S. The mean speed of stream in
S
which such a propeller works is therefore V + 5
and the real slip of the propelling apparatus, which
g
is a measure * of its efficiency, would be 5, but the
speed of the race is Y + S, and the real slip of the
water is S. Such a propeller might show a con-
siderable amount of apparent negative slip if placed
behind a ship and in a following current, a condi-
tion which is of course essential, as if it were pro-
pelling a phantom ship (see p. 58) the apparent
slip would be the same as the real slip, viz. — .
It is impossible to make an open screw which
THE SCREW. 21
shall not rotate the water, but the finer the pitch is
the less the rotation will be.
Mr. Thornycroft has shown that the relation
between the amount by which the race is accele-
rated forward and aft of the screw respectively may
be expected to depend upon the amount of the
rotation produced. A screw of coarse pitch-ratio
which will rotate the race considerably, will pro-
duce a large proportion of the whole acceleration
before the water reaches the screw, leaving only a
small part to be imparted abaft it. When the
rotation is a maximum, tlie whole acceleration is
produced by suction, and the speed of the stream
on meeting the propeller is V + S, in which case
the real slip of the screw is equal to the real slip of
the water S. All open propellers, by which is
meant propellers which are not confined in a casing
like the screw-turbine, occupy some intermediate
position, and are working in a stream with a velo-
g
city varying between V+ S and V+^, depending
upon the greater or less rotation of the race.
Hence the finer the pitch-ratio the more favourable
would be the conditions for obtaining apparent
negative slip, and it is found to be invariably the
case that it only occurs under these conditions, and
that it may be increased by still further reducing
the pitch of screws exhibiting it (see p. 16).
There are a number of pitchometers made which
will measure the pitch of a screw with sufficient
22 MASINE PROPELLERS.
accuracy if it is uniform. They are not to be
depended upon for the measurement of increasing
pitches. The operation may be performed without
instruments, as follows : —
Strike an arc of a circle a h, Fig. 6, concentric
Pj^ ^ with the axis of the propeller,
upon one of the blades with
any radius B. Divide the arc
into a number of equal inter-
vals, as 1, 2, 3, 4, 5. Measure
off the same number of in-
tervals upon a base>line xy,
Fig. 7, making them equal to
the developed length of the
intervale upon the arc. Mea-
sure the ordinates at each in-
terval on the arc from a plane
perpendicular to the axis of the propeller, and lay
off the ordinates 1 1', 2 2', 3 3', &c., at the corre-
sponding intervals on the base-line. Draw a line
CD through the points 1', 2', 3', &c., and produce
TBE SCREW.
23
it to cut the base in C. If the pitch is uniform
C D will be a straight line. Measure off from C a
length OE equal to the circumference of the circle
of R radius, and erect a perpendicular at E cutting
C D at F. E P is the pitch of the screw. If the
pitch is not uniform the points 1', 2', 3' will lie in
a curve. Tangents must be drawn to the curve
at the extremities 1' and 5', and the pitch of each
measured separately, see Figs. 8 and 9, and the
Via. 8.
mean of the two will be the mean pitch of the
screw. Measurements should be made of each
blade and at a number of different radii, and the
24 M AH INK PliO PELL Ens.
mean of all the readings taken as the mean pitch.
If the i^itch is uniform, and great accuracy is not
required, choose any two points on the arc ah,
Fig. 6, such that radial lines from them to the
axis subtend an angle of 30°. The dijQFerence
between the length of the ordinates of these points
to a plane at right-angles to the axis, measured in
inches, is equal to the pitch in feet.
The pitch of small model screws used for experi-
mental purposes can be most readily obtained as
follows : — Make a cylinder of wood of a diameter
about two-thirds that of the propeller. Fit a short
mandril to represent a piece of the shaft into the
boss, and pass the mandril through a hole in the
axis of the cylinder which has been bored to fit it.
Wrap a sheet of paper round the cylinder, securing
it with an elastic band, and cut the edge accurately
to fit the face of the blade. The direction of the
axis F E should be marked upon it. When the
paper is taken off* the cylinder and unrolled, the
edge which fitted the face of the blade will form a
straight line as C F, Fig. 10, if the pitch is uniform,
and if D be the diameter of the cylinder, then
rr-p: =-Yr ,<—.-:. If thc Wadc is not of uniform
C E D X 314
pitch it will form a curved line, and the pitch of
the leading and after edge must be obtained by
drawing tangents to the extremities of the curve
as already described.
It is sometimes useful to be able to estimate
THE SCREW.
25
roughly the pitch of a screw at sight. This may
be done by observing at what radius the Wade
makes an angle of 45° with the axis ; the pitcli is
Cfjual to the circumference at this radius.
Fir,. 10.
The screw was brought into successful operation
as a propeller by Ericsson and Smith in 1836.
The Archimedes^ a screw vessel of 237 tons
burden, was built by the latter in 1839. The
screw used was a single threaded helix of one
complete convolution. A double thread of half a
convolution was afterwards tried and found to be
an improvement ; but the best result was obtained
with two threads and one-sixth of a convolution.
The Earl of Dundonald in 1843 patented a pro-
peller with the blades thrown back as shown in
Fig. 11, the object being to counteract centrifugal
motion of the water, supposed to be caused by the
rotation imparted to it by the screw.
When a propeller is not sufficiently immersed to
prevent it from drawing down air, it is probable
that centrifugal action takes place, and that the
column of water takes the form of a cone with the
26 MARINE PROPELLERS.
screw for an apex ; but when no air gets to the
propeller, observation of its action in the phospho-
rescent water of tropical seas appears to show that
an ordinary screw does not disperse the water, but
Fig. 11.
SD
projects a column more or less cylindrical, and
having the appearance of a twisted rope, the
strands of which unravel themselves as they pass
astern.
In 1849 Robert Griffiths patented a self-govern-
ing propeller, which he thus describes : — "If the
screw moves with greater velocity than usual, the
increased resistance of the leading edge shall
correspondingly increase the pitch, thus increasing
the resistance and bringing down the revolutions."
The propeller chiefly associated with his name is
shown in Fig. 12, which represents the form now
adopted in the British Navy. The principal
feature in the Griffiths screw is the large boss,
which, while not impairing the efficiency, enables
the blade to be fixed in such a manner that the
* See a paper by M. Marchal in the * TraDsactions of iho
Institute of Naval Architects,' 1886, xxvii. p. 288.
TUB SOBEW. 27
pitch can be readily altered. This is an important
consideration, ae it is difficult to fix upon exactly
the right pitch in designing a propeller to run at a
given number of revolutions.
The Hirech screw is shown in Fig. 13. It has
an increasing pitch, and the propelling surfaces are
so formed as to throw the, water somewhat towards
the axis.
The Mangin propeller, Fig. 14, eonsista of two
narrow-bladed screws set behind one another on
the screw*ehaft with a space between them. It is
supposed not to rotate the water so much as other
screws.
28
MARINE PROPELLERS,
Rigg's propeller had a fixed screw or guide-
blades placed behind the revolving screw, with the
blades set at the reverse angle, so as to take the
Fig. 13
rotation out of the water and leave it moving*
directly astern. Rankine and Napier patented a
modification of this idea in the form of a twisted
rudder, of which the part above the screw-shaft
bends in one direction and the part below in the
opposite.
Screws have been tried with the pitch in the
centre less than the pitch at the circumference, so
as to allow the central part simply to follow up
the water.
THE SCREW,
29
' The Thornycroft screw, Fig. lo, which has
proved very successful, has an increasing pitch at
the middle of the blade, but it gradually becomes
Fio. 14.
uniform towards the root and towards the tip, the
reason being that at the root the rotation is already
excessive, and it is consequently not advisable to
so
MARINE PROPELLERS.
increase it by increasing the pitch, and towards the
tip, if it is attempted to accelerate the water too
much, it escapes round to the back of the blade.
Fig. 15.
The blades are also thrown back after the fashion
of the Dundonald propeller, but, instead of being
straight, they are convex on the driving face.
An ingenious attempt to make use of a certain
amount of energy said to be wasted by the screw
has been made recently by MM. des Gofifes and de
George. The inventors say that the viscosity or
resistance to rupture of the water in which any
helical propeller revolves, causes an appreciable
current to be set in rotation just beyond the tips of
the screw-blades. It is contended that a series of
helical surfaces, opposed in direction to those of the
screw proper, will receive a thrust from the revolv-
ing ring of water, which can be utilised for pro-
THE SCREW.
31
pulsion. The '* Antispire," as it is called, can be
placed around a propeller of any form. It is shown
in Fig. 16. The only experiments with the appa-
ratus which the author has witnessed were made
Fig. le.
in a tank, and as there was no motion through the
water it was not possible to tell how much the
result would be affected by the friction of the ring
itself, but a large increase of thrust was found to be
produced by it, and it is possible that the friction
of the surfaces would be more than counterbalanced
and a real propulsive force exerted. It is reason-
able to suppose that there is an unutilised reservoir
32 MAIIINE PROPELLERS,
of wprk in revolving currents external to the pro-
peller disc. Rings or bands without helical blades
have been used for protecting screws and for giving
increased manoeuvring power, but these plain
rings do not increase the thrust or the efficiency of
the screw, and the addition of the blades would
certainly be found advantageous in such cases, and
may be worthy of a still wider application.
In some double-ended ferry-boate, both in this
country and America, screws have been placed at
both ends of the vessel, for what appear to be
suflScient reasons connected with the service which
they have to perform. In the well-known Mersey
boats there are four screws, but in a new ferry-
boat, the Bergen^ built in America, two only are
employed, one forward and one aft, driven by the
same shaft — an arrangement which appears to be
inferior. The forward screw of the Bergen is
estimated to augment the resistance of the hull by
23 • 5 per cent., and its propelling efficiency is only
43 per cent, of that of the after screw.
There is no doubt that the best position for a
screw is at the stern. As a vessel moves through
the water the friction of the sides and bottom
imparts motion to a layer of water which increases
in thickness towards the stern, so that a consider-
able quantity of water is left with a motion in the
same direction as the vessel. If the screw works
in this water it is able to recover some of the
energy which has been expended by the ship in
TUE SCREW, 33
giving it motion. The speed of this wake, which
Rankine estimates may be as much as one-tenth of
the speed of the vessel, depends not only upon the
form, but upon the nature and extent of the sur-
face. It would not be desirable to increase the
volume or the velocity of a wake for the purpose
of improving the efficiency of the propeller, be-
cause this very surface friction proves to be the
largest portion of the resistance of a ship at
moderate speed; but as it is a necessity that
there should be a wake, it is a distinct advan-
tage to place the propeller in it and allow it to
utilise as much as possible of the energy it finds
there.
This frictional wake must not be confused with
deag water, which is water eddying behind a bluff
stern, an3 whicb has acquired the full velocity of
the vessel. When once the speed of the vessel has
been imparted to this water, not much energy is
wasted in maintaining it. If it is drawn out by
the screw, fresh water must take its place, and
there will be a continual drain of energy from the
ship, as the inflowing water must in its turn have
the full forward velocity imparted to it. Dead
water is almost a thing of the past, and is met
with only in the case of very full ships.
If a screw is placed behind a stern so bluff that
the supply of water is impeded, it will draw in
water at the centre of the driving face, and throw
it off round the tips of the blades like a centrifugal
D
34 MARINE PROPELLERS.
pump. The effect upon the ship is then peculiar.
Sir Frederick Bramwell has described a vessel
which went astern whichever way the screw was
driven, the reason being that a very bluff stern
caused the screw to act as described, and a loss of
pressure was produced upon the stem of the
vessel.
It is very important that a propeller should
have sufficient immersion, since if it breaks the
surface of the water the efficiency is reduced to a
remarkable extent (see Plate 1) ; but if it is suffi-
ciently far below the surface to prevent it from
drawing air, any further immersion within the
limits that can practically be obtained is of little
value. The speed with which water can follow
up the blades of a screw depends upon the head
of water over them, but when air is excluded the
equivalent of a head of 30 feet is supplied by the
atmosphere, and this being elastic and having
practically no inertia to resist sudden motion, its
pressure is more effective than that of a column
of water of equivalent weight.
It is probable that the inequality in the onward
motion of the layers of water forming the frictional
wake, accounts to some extent for the vibration
caused by the screw, since each blade in revolving
meets with an alternately diminished and increased
resistance. An ingenious mechanical contrivance
was invented by Griffiths, by which the blades
were made to adjust their pitch to suit the resist-
THE SCHEW. 35
ance, the pitch of a blade being reduced when
passing through the upper part of the circle, and
increased when passing through the lower part.
The apparatus would not stand much wear and
tear. Unless a propeller has a good running
balance it will tend to cause vibration. To insure
steadiness when revolving at high speed, it is
necessary that each blade should be of the same
weight, and that the centre of gravity of each
should be at the same distance from the axis of
the shaft.
There is a disadvantage connected with an in-
clined screw-shaft, which has been generally over-
looked. The result of depressing the end of a
shaft is to cause the effective pitch to vary through
every part of the revolution. If the inclination
be supposed to be 45° for example, that part of the
blade which is intended to have a pitch of three
diameters, has, in reality, an effective pitch vary-
ing from nothing to infinity. It is, of course,
obvious that the pitch of the blades in relation to
the axis is unchanged by any alteration in the
direction of the shaft, but whatever the pitch in
relation to the axis may be, if the axis were to pass
vertically out through the bottom of the ship, the
virtual or effective pitch, measured in the direction
of motion, is nil. If a screw does not move along
but has a motion of rotation only, the resistance of
the water to the blades is the same whatever be
the direction of the shaft, but if the propeller be
D 2
36
MARINE PROPELLERS.
Fig. 17.
allowed to move along while at the same time it
be constrained to move horizontally, the shaft
being inclined to the horizontal, then the resist-
ance of the water to the blades is not uniform, but
varies over every part of the revolution. This
will perhaps be made clearer by an examination of
the phases through which a blade passes during
one revolution. It is convenient and suitable to
consider the action of a screw as similar to that of
an inclined plane moving
past the stern. In Fig. 17
the full line represents the
upper blade as a plane
moving from port to star-
board, the dotted line repre-
sents the lower blade as a
plane moving from star-
board to port. In Fig. 18
the shaft is horizontal, and
the full line shows the blade
going down, and the dotted
line the blade coming up.
In Fig. 19 the shaft is in-
clined at 45°, the full line
again shows the blade going
down, and the dotted line
the blade coming up. Now
as the ship moves forward
the water flows to the sc^'ow in approximately
horizontal lines, and the blade which at one part
Fig. 18.
Fio. VX
7
]
THE SCREW, 37
of the revolution is edgewise to the water, at
another is square on to it, and the result is a
succession of shocks causing vibration. Another
way of looking at it is this : — A particle of water
meeting the ascending blade has its motion rela-
tive to the vessel arrested completely, while a
particle first meeting the forward edge of the
descending blade would require to have its velo-
city infinitely accelerated in a horizontal direction
to enable it to escape from under the blade. This
is what is meant by saying that in the above
example the effective pitch varies from nothing to
infinity during each revolution.
The racing of screws is due to either of two
causes. If the propeller breaks the surface of the
water as the stern rises in a seaway, it will draw
air down, and the resistance is immediately very
much reduced. Referring to Plate 1, where the
thrust is shown at different revolutions of a pro-
peller, both when completely immersed and also
when splashing, it will be seen that in the former
condition a thrust of 11 lbs. is exerted at 680
revolutions. When air is drawn down, the same
thrust is exerted at 1000 revolutions, so that this
propeller, if delivering a constant thrust, would
vary its revolutions very rapidly from 680 to 1000
if alternately raised and lowered as in the action of
pitching. But it is not only when the screw breaks
the surface that it will race. If a vessel is among
waves, racing may occur, although the screw may
38 MARINE PROPELLERS,
not be emerged at all. Mr. Froude pointed out
that this was probably due to the circular motion
of the particles of water in waves. There is no
real motion of translation in waves, the water
which is travelling in one direction at the crest
returns in the opposite direction in the trough.
This circular motion extends to some distance
below the surface, and a screw finds the resistance
of the water augmented or reduced, as it is beneath
the trough or crest of a wave, and reduces or
increases its speed accordingly.
A screw causes lateral motion of the stern of a
vessel which has to be counteracted by the rudder.
This efifect is very much greater when going astern
than when going ahead, but the cause is not the
same in the two cases. When going ahead Pro-
fessor Osborne Reynolds has pointed out that the
onward motion of the frictional wake is very
different at the surface and at the keel. He agrees
with Rankine that the mean speed of the wake in
the case of a vessel of fairly fine form may be
10 per cent, of the vessel's speed, but thinks it
varies from 20 per cent, at the surface to nil at
the keel ; the upper blade of the screw therefore
experiences more resistance than the lower, and
tends to drive the stern round. If the screw is
right-handed, and does not draw air down, it will
tend to cause the vessel to carry a starboard helm
in order to maintain a course. If there is air in
the wake, caused for example by the vessel being
THE SCREW. 39
at a light draught of water, the effect is reversed,
the lower blade predominates, and port helm must
be carried. The natural effect of the screw may
also be neutralised or even reversed if there is a
broad counter over it and a large rudder, especially
if, as is often the case, the part of the rudder
behind the upper blade of the screw is larger in
area than the part behind the lower blade. The
reaction of the stream of water thrown from the
upper blade upon the counter and upper portion
of the rudder is greater than that of the stream
thrown from the lower blade in the contrary
direction upon the lower portion of the rudder, and
may necessitate the carrying of a port helm with
a right-handed propeller. Professor Eeynolds
states that a right-handed screw without air
always bears considerably on the port side of
the stern-post, even when the ship carries a
port helm, showing that the effect on the hull
and rudder more than counterbalances the effect
on • the screw. In the Engineer of October Ist,
1886, was published a diagram showing the
port and starboard strains upon a rudder as
recorded automatically by Maginnis' "Rudder-
graph." The screw was right-handed, and the
diagram showed clearly that the ship required a
starboard helm to keep a straight course.
When the screw is reversed, and the vessel has
gathered stern way, the propeller has a much
greater influence upon the course of the ship than
40 MARINE PROPELLERS,
when going ahead. In the latter case the
influence is always very small ; in the former it is
often great. The engines will be observed to have
a great tendency to race when going astern. The
screw is then drawing air, and the upper blades
suffer most, so that the lower blades experience the
most resistance, and drive the stern round. A
right-handed screw tends to move the stern to
port, and a left-handed one to starboard.
When a screw is suddenly reversed, and before
the headway is off the vessel, the action of the
rudder is not to be depended upon. The following
is an extract from the report of the Committee
appointed by the British Association to investigate
the effect of propellers on the steering of vessels.
British Association Report^ 1878.
'< It is found an invariable rale that daring the interval in
which a ship is stopping herself by the reversal of her screw,
the rudder produces none of its usual efiToct to turn the ship,
but that under those circumstances the efifect of the rudder,
such as it is, is to turn the ship in an opposite direction from
that in which she would turn if the screw were going ahead.
The magnitude of this effect is always feeble, and is dififorent
for different ships, and even for the same ship under different
conditions of loading. It also appears that, owing to the feeble
influence of the rudder over the ship during the interval in
which she is stopping, she is then at the mercy of any other
influences that may act upon her. Thus, the wind, which
always exerts an influence to turn the stem of the ship into
the wind, but which influence is usually well under control of
the rudder, may, when the screw is reversed, become paramount,
and cause the ship to turn in a direction the very opposite of
that which is desired.
" Also the reversed screw will exorcise an influence, which
THE SCREW. 41
increases as the ship's way is diminished, to torn the ship to
starboard or port, according as it is right or left-handed, this
being particularly the case when the ship is in light draught.
These several influences — the reversed effect of the rudder, the
effect of the wind, and the action of the screw — will determine
the course the ship takes during the interval of stopping.
" They may balance, in which case the ship will go straight
on, or any one^of the three may predominate."
Notwithstanding that a screw has a tendency, as
just described, to produce sideways motion of the
stern, and so to cause a vessel to deviate from a
straight course, it yet offers considerable resistance
to lateral movement produced by external causes.
The pressure on the blade which is moving in the
same direction as that in which the stern of the
vessel is turning is increased, while on the blade
moving in the opposite direction the pressure is
reduced, that is to say, if the screw is right-handed
and the vessel is under port helm, the stem, conse-
quently, travelling to port, the resistance of the
lower blade which is moving towards the port side
will be increased, and the resistance of the upper
blade, which will be moving towards the starboard
side, will be diminished, because the one is meeting
the water, and the other is receding from it. The
change of pressure will be proportional to the
square of the angular velocity of the stern. The
irregular pressure causes the vibration frequently
noticed when a screw vessel is rapidly turning.
This resistance to lateral motion is not without
value, because if it is removed the condition of a
42
MARINE PROPELLERS.
Fig. 20.
vessel moving in a straight line is one of instability'-.
If the vessel makes the least angle to the direction
in which she is moving, the excess of pressure due
to undisturbed water at the bow tends to increase
the divergence, and this tendency is resisted by
the propeller. It seems probable that a vessel
never maintains a line of advance in the exact
direction of its axis, but always at a small angle
with it.
A very ingenious propeller has lately been
patented by Mr, F. H. White,
which, while retaining the
advantage of rigid blades
in resisting lateral motion
when a vessel is on a straight
course, is so arranged that
the blades are under control
and can be feathered in such
a way as to cause them not
only to offer no resistance
to turning, but to actively
assist in it. It is in fact a
steering propeller of a very
simple description. It is
illustrated in Figs. 20, 21, 22.
The screw-shaft terminates
in a universal joint which
connects it with an exten-
sion of itself in the form of a smaller shaft or
tail-piece. The joint can be made in several
TBE SCREW.
foi-rae, but the simplest is shown in Fig. 20
where the centre or connecting piece has four
arms at right angles to each other. The blades
are rigidly fixed to tlie two arms which are di-
rectly held by the jaws of the main shaft. See
Fig. 20, which ebows the screw in elevation.
Any movement of the tail-piece causes an altera-
tion in the pitch of the blades, an increase in the
pitch of one blade being accompanied by an equal
44
MARINE PROPELLERS.
decrease in the pitch of the other. The eflfect of
the change of pitch is that the stem of the vessel
is forced either in one direction or the other,
Fig. 22.
according to which side the tail-piece is moved.
When it is desired to change the course of the
vessel to the right, the tail-piece is moved to the
right, its manipulation being thus similar to that
/
THE SCREW, 45
of the rudder to which it may be attached as
shown in Figs. 21 or 22, The joint is covered
with a light casing as shown in Fig. 21. The
screw may have two, three, or four blades. A
characteristic which adds much to the practical
value of the design, is that the feathering of the
blades is greatly assisted by the action of the
water-flow itself, as any alteration in the course
of the vessel tends to change the pitch of the
blades in such a manner as to bring the tail-
piece into that position which would of itself cause
such an alteration, so that after having initiated
the feathering motion, it may be anticipated that
the tail-piece will have little more to do than to
control and regulate it.
When auxiliary steam power has to be applied
to sailing vessels, it is best, if possible, to arrange
the screw so that it can be lifted out of the water.
If disconnected and allowed to revolve it causes
considerable resistance. If it cannot conveniently
be lifted, it is advisable to use a screw with two
narrow blades, which can be set up and down in
a line with the stern-post, and feathered fore and
aft by internal mechanism as arranged by Bevis.
With a view of reducing the drag under sail to a
minimum, Messrs. Thornycroft tried a propeller
with flat blades, which could be feathered in line
with the shaft for sailing, and set at an angle
with it for steaming, but it was found to be a very
inefficient propeller, requiring just double the
46
MARINE PROPELLERS,
horse-power for a given speed as was needed for
an ordinary screw. Fig. 23 shows the results
obtained with it, compared with those given by
an ordinary screw by which it was afterwards
replaced.
FiQ. 23.
300
£50
P
X
200
I
►
.2
-a
ISO
00
50
05
IMP. ^^
■LAPIP fWOyELLIW
Bi>S5S-
^^^j^jS^rScrsiiiS
.ettj!
600
600
400
*
300 ^
«S
I
- 200
100
II ilE I&
Speod in knots.
Compai:atiTe trial with common and with flat-bladed propellers.
Vessels intended for towing require large screws,
because, if the screws are designed to work at their
best efficiency against the small resistance of the
tug alone, the slip when towing will be excessive,
and will cause an undue wast^ of power. It is
desirable to so design the propeller that it shall
give a maximum return at the speed which the
THE SCREW. 47
tug may be expected to attain when towing an
average load.
' Screws for electric launches labour under the
disadvantage of having to run at an exceptionally
high speed of revolution. The blades should be
very thin and sharp, and two blades will give less
resistance to turning with a given surface than
three. It is difficult to estimate the pitch necessary
to give a required number of revolutions, because
it is a peculiarity of the motor, that the slower the
rate at which the screw turns, the faster the power
is run down, and vice versd. It may be compared
in this respect to the steam siren which uses a large
amount of steam when revolving slowly, and the
more rapid the rate of turning the less is the
quantity of steam passed.
The fastest running screws of which the author
has had experience were made by Messrs. Thorny-
croft, for the Howell torpedo. They are 6 inches
in diameter, and run at 5000 revolutions per
minute, driving the torpedo at 30 knots.
Twin screws possess very many advantages over
a single screw, and are quite as efficient. In very
fine ships the length of the outside shafting
becomes a serious consideration, and the necessary
supports add to the resistance. In order to reduce
this inconvenience to a minimum, the well-known
firm of Rankin and Blackmore introduced an
arrangement of twin screws with overlapping discs
in the 'tug Otter, built in 1876, One propeller
48
MARINE PROPELLERS,
was set in front of the other, the. blade-tips passing
through an aperture in the dead wood. Figs, 24
and 25 show twin screws as fitted in the Buzzard^
a small coasting steamer belonging to Mr. John
Burns. The arrangement has proved successful,
Fig. 24.
and has been frequently adopted, the most notable
examples being the s.s. Teutonic and Majesticy built
by Messrs. Harland and Wolff. The screws of the
Teutonic are 19 feet 6 inches in diameter, and the
distance between the shafts is IG feet. One screw
is 6 feet 3 inches behind the other. They are right
and left-handed, and turn outwards. In a twin
screw torpedo boat built by M. Normand, with
overlapping screws, both are arranged to turn the
same way. The overlapping blades thus cross one
another, and the water thrown up by the ascending
TSE SCREW. 49
blade of one screw is met by tlie descending blade
of the other, and the slip is reduced. It is found
tbat when so arranged, the aftermost propeller
turns slower than the foremost one, the contrary
being of course the ease when they turn in opposite
directions.
Fio. 25.
Triple screws have not as yet been widely
introduced. An interesting series of comparative
trials with twin and triple screws was made by
M. Marcbal at Lorient, and described by him in a
paper read at the Institution of Naval Architects
in 1886. His summing up of the results is that
" three screws are, from the point of view of speed,
very nearly equivalent to two screws of the same
propulsive surface and immersed to the " same
50 MARINE PROPELLERS.
depth, when the most favourable position is chosen
for each system." * Recent examples of the
application of three screws are the French armoured
cruiser Dupuy de Ldine^ and the United States
cruiser known as No. 12, of 21 knots speed and
20,000 I.H.P., and some Italian torpedo cruisers
engined by Messrs. Hawthorn, Leslie, & Co.
There would appear to be several advantages to
be anticipated from the adoption of triple screws
in high-speed ships of war. It is possible by this
means to effect a reduction in weight of machinery
since a higher speed of revolution is admissible.
There would probably be a saving of fuel when
cruising at slow speeds by using the centre screw
alone. In twin screw ships of small beam in pro-
portion to length, it is more economical to use one
propeller only at slow speeds, and to disconnect
the other, as the drag of the idle screw and of the
small angle of helm required to maintain a course,
are more than compensated for by the reduction
of engine friction and the superior economy of
steam obtained by working one engine at a greater
proportion of its maximum power, and a still
further economy might be expected from the
increased subdivision of engine power in triple
screw ships.
* TranSi Inst. Naval Arcbitects, xxyii. p. 239.
( 51 )
CHAPTER IV.
EXPERIMENTS WITH MODJILS AND THEIR APPLICA-
TION TO THE DETERMINATION OF THE MOST
SUITABLE DIMENSIONS.
For a screw of any given pitch-ratio, there is
a particular slip - ratio corresponding to its
maximum efficiency. A greater or less amount of
slip than this will result in a smaller return of
useful work in proportion to the power expended
in driving the screw. By slip-ratio is meant the
ratio P R to V, where
P = mean pitch ;
R = revolutions ;
V = velocity of feed, or speed of screw through
the water.
The best way of determining the slip -ratio
which is suitable for any given ratio of pitch to
diameter is by experimenting upon a series of
model screws of some selected type, each diifering
only in the ratio of pitch to diameter, and the
following conditions maybe laid down as essential,
if the results obtained are to be useful for general
application : —
1. Each model must be tried at a number of
different slip-ratios.
E 2
52 MARINE PROPELLERS.
2. The velocity of feed must be capable of
accurate measurement.
3, The power expended in driving the screw
must be measured, and it must be the power put
into the screw-shaft, and not complicated with
engine friction, which is an unknown quantity.
It is clear, therefore, that no experiments would
be satisfactory, in which the screw under examina-
tion was working in the wake of a vessel, because
it would then be impossible to measure the velocity
of feed, since the forward motion of the wake is an
unknown quantity, and varies with the speed of
the ship in an unknown manner.
The late Mr. W. Froude, by means of an ideal
conception of a small element of helical surface,
rotating at the end of a non-resisting radial arm,
deduced by theory for the screw, results very similar
to those which were afterwards yielded by experi-
ment.* In 1877, Mr. Froude described how such
experiments were being conducted at Torquay ,f
and a very full account of the system pursued, not
only for ascertaining the screw efficiency, but also
for investigating the effect upon the operation of
the screw of the presence in front of it of the hull
of the ship, was given by Mr. R. E. Froude in
18 83. J All these papers should be consulted by
any one proposing to experiment for themselves.
* Trans. Inst. Naval Architects, xix. p. 47.
t Proc. Inst. Civil Engineers, li. p. 38.
\ Trans. Inst. Naval Architects, xxiv. p. 281.
EXPERIMENTS WITH MODELS. 53
In the years 1879-80, Mr, John I. Thornycroft
made a number of experiments with models of
small dimensions, and a detailed description of
these will be given as they are interesting as
showing what can be done with moderately simple
appliances.
The models were about 9 inches in diameter,
and this size was found to be convenient. The
maximum thrusts did not exceed 30 lbs., so that
although the scale was large enough to admit
of accurate measurement, a moderately small
dynamometric apparatus could be employed. They
were made as follows : — A wooden block was pre-
pared from the reduced propeller drawing, upon
which a blade was modelled by hand in paraffin.
A mould of the blade was made in plaster of paris,
into which was run an alloy consisting of tin and
bismuth, the latter in small proportions. This
material is sufficiently soft to be scraped and cut
with a knife, and at the same time is strong enough
to retain its form. It, of course, does not rust.
The cast blade was then filed, burnished, and
accurately fitted to the wooden block if it had
become at all distorted. The blades were secured
in the boss by screws in such a way that the pitch
could be varied to any desired extent. A steam
launch was fitted up with a small shaft passing
through the bow to carry the model screw, the
shaft projecting a sufficient distance in front of the
launch to ensure that the model should work in
64 MARINE PROPELLERS.
undisturbed water. This shaft could move very
freely in its bearings to and fro, and the end of it
was attached by means of a steel pianoforte wire
to a spring, so that the thrust exerted by the pro-,
peller could be recorded. This shaft was made to
revolve by means of a gutband working on to a
pulley, and driven by means of a small engine of
one or two horsepower. The measurements made
were : —
1. The thrust exerted by the model.
2. The revolutions of the model.
3. The speed of the launch.
4. The turning effort expended in driving the
model.
5. Equal intervals of time.
The constant friction of the engine and shafting
was also measured in order to get the true zero for
the turning effort diagram. A dynamometer was
constructed, by which records were continuously
made upon a revolving drum driven at a uniform
speed by means of clockwork. A number of pens
over the drum were each connected to an electro-
magnet in such a way, that so long as no current
flowed the pens were stationary, and traced straight
lines upon the paper as it revolved beneath them.
When contact was made the pens were jerked and
made a lateral indent in the line. One pen was
electrically connected with a clock, and measured
intervals of time, making an indent every 12
seconds. A second pen recorded the revolutions
EXPERIMENT8 WITH MODELS. 55
of the main engine driving the Jauneh, these
revolutions aiFording a means of checking the
speed. A third pen recorded the revolutions of
the model, a counter on the shaft making contact
every 50 revolutions. The speed of the launch
was found by passing a fixed distance on shore
of 300 feet, the time of passing the posts being
marked by an electric pen actuated by the observer
pressing a button. As the observations were taken
in a tideway two runs were necessary to determine
the speed for every observation, one upstream
and one down. Another pen was connected to a
spring before mentioned, to which the model shaft
was attached, and recorded the extension of the
spring and thrust of the propeller. The last pen
showed the tension of the gut driving the model,
and thus measured the turning eflfort upon the
shaft. This tension was obtained by the arrange-
ment shown in Fig. 26. The large pulley in the
centre is driven by the small engine of which the
cylinder, piston-rod, connecting rod, and crank-arm
are indicated in the figure. The lower pulley is
on the shaft of the model propeller. The two
upper pulleys are carried by a bar pivoted at the
centre. Rigidly attached at right angles to this
bar is a long lever, the weight of which is balanced
by the ball at the top. The motion of the lever is
limited to a short travel on each side of the vertical
by stops not shown in the figure. A spring is
attached to the bottom of the lever, and its exten-
MARINE PROPELLERS.
sion is automatically recorded upon the diagram.
The driving band is passed round the pulleys as
shown, the direction of its motion being indicated
by arrows. When the central pulley is made to
revolve, the tension of the gut pulls down the left-
hand pulley, and extends the spring until its
tension is sufficient to prevent further motion of
the lever. An adjustment is provided in the cord
between the spring and the lever, eo that the latter
may be maintained approximately vertical.
If Ta is the tension of the ascending or tight
side of the hand, T, the tension of the descending
EXPERIMENTS WITH MODELS. 57
or slack side, and P the pull in pounds as measured
by the spring, then
and turning moment = (Tj — Ti) x 2 ir r x revo-
lutions of r per minute.
The launch, which as before stated was driven
by an independent screw, maintained an approxi-
mately constant speed of about 4^ knots, and a
number of observations were taken at different revo-
lutions of the model and plotted as shown in Plate 1.
Curve A is the thrust of the model, B is the useful
work in foot-pounds per minute, being the product
of the thrust into the speed through the water.
C is the work expended in foot-pounds per minute.
The useful work divided by the work expended is
a measure of the efficiency of the model as shown
by curve D.
A convenient way of utilising the results thus
obtained is to construct a series of constants, which
will express the relation between disc-area, power,
and speed, at different slip-ratios. A second series
of constants can be formed expressing the relation
between diameter, speed, and revolutions. These
constants depend upon the following laws : —
1. For a given pitch-ratio and efficiency the
disc-area is proportional to the horse-power, and
inversely proportional to the cube of the speed.
2. For a given pitch-ratio and efficiency the
revolutions per minute are proportional to the
58 MARINE . PROPELLERS,
speed, and inversely proportional to the diameter.
They might take the following forms : —
01 = disc-area in square feet x
H.P.
Cb = revolutions per minute x — •
V
Where i; = velocity of feed ;
H.P. = effective horsepower in the screw-shaft.
In this shape, however, it would only be possible
to obtain from them directly the proportions
proper for a screw to propel a " phantom ship " —
that is a ship which would require the same thrust
to propel it at any given speed as a real ship, but
which will create no disturbance in the water,
driven by a " phantom engine "—that is an engine
without friction. In order to make them available
for general use, it is more convenient to substitute
V = speed of ship for v = velocity of feed, and
I.H.P. for effective horsepower in the shaft. In
order to do this it is necessary to make certain
assumptions as to the speed of the following
E H P
current and as to the ratio ' ' ' and as these
I.U.P.
will vary with the form of the ship and with the
type of engine respectively, an element of un-
certainty is here met with, and much will depend
upon the judgment of the designer, as to whether
it is necessary to apply a wake correction or a
propulsive coefficient correction, or whether the
standard values assumed for these factors may be
supposed to be a sufficiently close approximation.
EXPERIMENTS WITH MODELS. 59
The standard wake has been taken as 10 per
cent, of the speed of the vessel. In a very full
ship it might be as much as 30 per cent. There-
fore V the speed of the ship should be reduced,
when using the constants, by 20 per cent, for a
very full ship, and by amounts varying from
20 per cent, to nil, as the fulness of form varies
from *' very full " down to what may be considered
a " fairly fine " vessel when no correction need be
made.
Table II. p. 74 gives the value of the wake cor-
rections for a few vessels. The standard ratio of
' ' ' has been taken as "5. A correction can
I.H.P.
be made for any deviation from this assumed value.
If, for example, the E.H.P. is estimated at 55 per
cent, of the I.H.P,, the I.H.P. must be multipliM
by the ratio j^tt .
•^ 50
Again, the constants are primarily correct for
four-bladed screws; they can be used for three-
bladed or two-bladed screws by multiplying the
I.H.P. by ^78(55 or ^Tgg respectively.
The form, therefore, which the constants finally
take is
lys
Oa = disc-area in square feet X jWp- >
D
Or = revolutions per minute X ^ •
Where V = speed of ship in knots.
60 MARINE PROPELLERS.
If constants are constructed in this way from
the curves in Plate 1 corresponding to different
amounts of slip, a row of figures is obtained, such
as is shown by any one of the horizontal lines in
Table I., p. 73, and these can be placed in their
proper relative position under a curve of efficiency.
For example, to find the constants C^ and Cr
corresponding to 750 revolutions of a three-
bladed model from the curves in Plate 1 : —
Diameter of model = 9 inches.
. * . Disc-area = * 441 sq. feet.
Work expended in foot-poonds = 9625.
Useful work ^ 6330 ^ ^^g ^ ^velocity of feed in feet
Thrust in pounds 14-8 \ per minute.
^ = 4-22 knots.
•441 X f4-22 X 4y
Ca = ^i '^ = 90.
•683 X -865
Ch= ^^^^'^^ = 120.
4-22 X .-i
The object Mr. Thornycroft had in view in
making the experiments was to test the efficiency
of the screw-turbine propeller as compared with
the screw he was then using on torpedo boats,*
and he therefore did not carry out a complete set
* See a paper by Mr. Thornycroft in Trans. Inst. Naval
Architects, xxiy. p. 42.
EXPERIMENTS WITH MODELS. 61
of experiments upon a common screw, which
would have involved a series of trials with a
number of models of varying pitch-ratio, but
contented himself with ascertaining that a small
change of pitch on either side of that for which
the propeller was cast, obtained by twisting the
blades in the boss, did not increase the efficiency,
but rather reduced it.
This complete series was, however, afterwards
carried out by Mr. R. E. Fronde at Torquay, and
the results were given by him in a paper read
before the Institution of Naval Architects in 1886.*
They corroborated generally those obtained at
Chiswick, except in one particular. So far as
could be judged by Mr. Froude, there was scarcely
any diflFerence in maximum efficiency within such
a large range of pitch-ratio as from 1 • 2 to 2*2.
As almost precisely the same maximum was
obtained by Mr. Thornycroft with a pitch-ratio
of 1 • 14, it seems reasonable to suppose that these
even may hardly be considered as hard and fast
lines beyond which efficiency will decline, and
Mr. Froude considers that they may be fairly
extended to • 8 on the one side and 2 • 5 on the
other.
It must, however, be borne in mind that
this equality of efficiency is manifested by screws
working in open water. There is a very general
consensus of opinion that small pitch-ratios give
* Trans. Inst. Naval Architects, xxvii. p. 260.
62 MARINE PROPELLERS,
the most favourable results in practice. If this
opinion is justified, the explanation must be that
large pitch-ratios cause a greater augmentation of
hull resistance. That this would be so might be
inferred from the reasoning on p. 21, which leads
to the conclusion that such screws produce a
greater suction than those of fine pitch. Although
accepting the parity of efficiency of different pitch-
ratios within the limits experimented upon, when
the screws are considered apart from the vessels
they propel, the author thinks that there is reason
to suppose that there will be a loss involved in the
use of a screw of coarse pitch, if it is placed in
such a position that the increased suction produced
by it is able to take effect upon the hull of the
vessel.
Mr. Froude also found a great similarity between
the curves of efficiency at different pitch-ratios,
the only apparent effect of change of pitch-ratio
being to cause the maximum efficiency to occur at
different slip-ratios. Where, for example, the
efficiency of one propeller reached a maximum at
15 per cent, slip, the efficiency of another of
different pitch-ratio was at a maximum at 20 per
cent, slip, and so on. It was therefore possible to
superimpose the curves and cause them to coincide
by the simple device of empirically changing the
scale of slip-ratio. Mr. Froude very kindly gave
the author permission to give the results of the
Torquay experiments in a paper for the Institution
EXPERIMENTS WITH MODELS. 63
of Civil Engineers on '* The Screw Propeller,* for
which purpose the author compiled Table I.,
p. 73, in which each horizontal line of figures
corresponds to a particular pitch-ratio and contains
constants for disc-area, and revolutions at diflFer-
ent amounts of slip as calculated from a set of
curves such as that shown in Plate 1, and in
the manner already described. These all occupy
their proper relative positions under the curve of
efficiency.
The table embraces the whole of the experi-
ments possible with a particular type of screw,
including pitch-ratios extending from 0*8 to 2*5,
and slip-ratios from the lowest to the highest
which is considered practicable.
It would be used in the following manner: —
Let it be supposed, for example, that the size of
the screw is limited by the draught of water. If
the given disc-area is multiplied by the cube of the
speed of the vessel in knots and divided by the
I.H.P., the constant C^ is obtained. Suppose it is
360. The nearest figure to this in the column under
the maximum efficiency should be sought, and its
position, when found, indicates the pitch-ratio 1*6,
which will be in the same line at the left hand of
the table. Adjoining the disc-area constant 360
will be found the revolutions constant 71. This
number, multiplied by the speed of the vessel in
knots, and divided by the diameter of the screw in
* Proc. Inst. Civil Engineers, cii. p. 74.
64 MARINE PROPELLERS.
feet, will give the number of revolutions at which
a four-bladed screw should run to obtain the
maximum efficiency.
It is evidently desirable to select the constants
from the column under the maximum efficiency,
but in special cases when the revolutions are
required to be either exceptionally high or excep-
tionally low in order to suit existing engines, the
same disc-area constant may be taken from one of
the other columns where it will be found associated
with either a lower or a higher value of Or accord-
ingly as the slip ratio is greater or less ; and it is
possible to see at a glance what sacrifice it is
necessary to make in efficiency in order to obtain
the required result.
If the product of the Or constant multiplied by
its proper pitch-ratio is greater than 101 • 33 the
apparent slip will be positive; if less, it will be
negative. The amount of the slip in either case
will be given by
Qxv * P^M - 101-33 ^ irtrt
Slip per cent = *- — i- — x 100 ;
where j9 = pitch-ratio.
The same constants are presented in a graphic
form in Plate 2, in which each vertical column of
Table I. is plotted as a curve and values of C^
and Or corresponding to intermediate pitch-ratios
may be thus obtained.
The method of correcting for two and three
blades and also for different values of wake is
EXPERIMENTS WITH MODELS, 65
due to Mr. R. E. Froude, and Table II. was given by
him for the purpose of fixing upon a suitable wake
correction in his masterly paper already referred
to,* which is worthy of the most careful study.
Mr. Fronde's screws were of uniform, pitch, and
the blades were elliptical. The width in the
middle of the developed blade was • 4 ~.
It follows that the developed surface, supposing
each blade to be a complete ellipse, would be
For a four-bladed scrow = disc-area X * 4
„ three „ = „ x 0*3
„ two „ = „ X 0-2
As the developed area is usually taken as ex-
clusive of the boss, the portions of the ellipses cut
oif by it must be deducted. A few examples of
the use of the tables will be given at the end of
the chapter.
It will be noticed that the disc-area constants in
the columns under maximum efficiency permit great
latitude in the choice of diameter for a given
I.H.P. and speed, so that if consideration is con-
fined to the screws alone apart from the vessels
they are designed to propel and the service these
vessels are intended to perform, within these
limits the efficiency is independent of the actual
size. For example, take the case of a vessel of
* Trans. Inst. NaVal Architects, zxyii. p. 250.
F
66 MARINE PROPELLERS.
good form having engines of 500 I.H.P. and
expected to attain a speed of 10 knots. From
Table I. equal efficiency may be expected with a
screw having a diameter of 10 feet and 0*8 pitch-
ratio, and with one having a diameter of 15^ feet
and a pitch-ratio of 2 • 5. The first would run at
138 revolutions per minute, the second at 33^.
Some remarks have already been made (see p. 61)
touching the eflFect of pitch-ratio upon efficiency,
but in considering the relative advantages of large
and small screws the duties required of the vessel
must be taken into account. Suppose it is desired,
for example, to maintain a high speed against
head winds and seas. It is generally sup-
posed that a large screw or a large surface is
all that is required, but if we consider what
happens when a vessel meets head winds we shall
see that this is not necessarily so. In such circum-
stances the speed of the ship is checked, the revo-
lutions of the screw remaining practically un-
affected, so that the slip-ratio is increased. If this
is already sufficient to give maximum efficiency
at the smooth water speed, the efficiency will be
reduced when the slip is increased by the wind,
and it is probable that the 15^foot screw of 2' 5
pitch-ratio would waste as much power as the
10-foot screw of • 8 pitch-ratio, although one has
nearly 2^ times the surface of the other, because
they both have the same position to start with as
regards the curve of efficiency. Large diameter
EXPERIMENTS WITH MODELS. 67
associated with large pitch-ratio is valueless for
the purpose ; what is required is that the slip-ratio
shall not be excessive when the speed of the vessel
is retarded by external resistances. The case is
analogous to that of a tug, and must be similarly
treated- The best proportions will be obtained by
designing for a speed less than the maximum
smooth-water speed, but such as the vessel is ex-
pected to maintain over an average passage. The
propeller would have a somewhat reduced efficiency
when the vessel was developing her full power
over the measured mile, would in fact be too large,
but would work at its best at the speed assumed as
the average, and should effect a saving of fuel on
the voyage. When the diameter is limited the
blade-surface may be increased with advan-
tage.
It has been stated by Mr. Hall-Brown * that for
vessels of very full form — a class with which he
has had much experience — a large diameter and a
small pitch-ratio are essential to success, and he
attributes the necessity to the influence of dead
water as distinguished from frictional wake (see
p. 33). In such a case the blades must reach well
out into water clear of the stern, so that the pro-
portion of dead water to the total area of stream
acted upon may be as small as possible. Mr. Hall-
Brown gives the particulars of what is found to
* Proc. Inst Civil EngineorB, cii. p. 131,
F 2
68 MARINE PROPELLERS,
be a good screw for a cargo vessel of the following
dimensions :—
Length B.P 277 feet
Beam (moaldod) 37*5 „
Draught 19 feet 11 inches
Displacement •• 4670 tons
Block coefficient -792
LH.P 825
Speed 9 knots
Diameter of screw 16 feet
Pitch „ 16 „
Reyolations 64
The values of C^ and Cr are 184 and 115 re-
spectively, which agree with the constants in the
table for 1*0 pitch-ratio at 69 per cent, efficiency,
but as the table is calculated for a wake value of
10 per cent., corresponding to a fine form of
vessel, he suggests that this points to the conclu-
sion that the propulsive coefficient is very low on
account of the action of the screw upon the dead
water, and that the two corrections for wake and
propulsive coefficient tend to annul one another.
In such a case it might be expected that a better
performance would be obtained if twin screws
were employed, as these would be to a great
extent clear of the dead water.
Whenever the ship is of exceptional form, no
exact rules can be given for the proportions of
screws deduced from model trials in undisturbed
water. Certainty can only be obtained by trying
the model screw behind a model of the ship, and
this is always done by Mr. Fronde in the case of
EXPERIMENTS WITH MODELS. 69
new Admiralty designs. But every carefully
recorded ship trial is in one sense a model experi-
ment of this character, and when a screw is to be
designed for a ship of a special type, it is safer to
calculate the values of C^ and C„ from the actual
figures obtained from the trials of some vessel, of
proportions as similar as possible, which has given
a good result, because the values of wake and
propulsive coefficient may then be assumed to be
similar also. In place of constructing constants,
the following more direct method may be
employed : —
To find the diameter of a propeller for a
given I.H.P. and a given speed from the diame-
ter of another similar propeller at a different
I.H.P. and a different speed.
If c2 =r diameter of model, which may be larger or smaller
than D ;
D = diameter of required propeller ;
p = I.H.P. of model ;
P = I.H.P. of required propeller ;
V = speed of vessel with model propeller ;
V = „ „ required „
r = revolutions of model propeller ;
R = „ required „
Then
and
/ v^ P
R = r X - X 1-
V D
The pitch-ratio must be the same as that of the
screw which is treated as the model.
70 MARINE PROPELLERS,
Examples in the use of Tables /. and IL
Example 1. — Find the diameter and revolutions
of a screw to work at maximum efficiency for a
vcsstJ of 20 knots speed and 6000 I.H.P. Pitch-
ratio to be 1 • 2.
The disc-area constant (Ca) in the table for this pitch-ratio
is 288.
The revolutions constant (Ck) in the table for this pitch-ratio
is 92.
Disc-area = C^ X ,c ?'^'f' , vs = 288 x-?^^=2168<i. ft.
(Speed m knots)* 2(y* *
.*. Diameter = lG*5feet.
T> 1 X- i-i speed in knots ^^ 20 ^ ^ ,
Eevolation8= Cr x -j^ — - — ^7—- = 92 x tt-t = HI-
diameter m leet 16*5
Example 2. — Find the pitch and revolutions of
a screw to work at maximum efficiency for a vessel
of 20 knots speed and 6000 I.H.P. Diameter not
to exceed 15*5 feet.
Disc-area =189 square feet.
6000
Ca = 189 X 777:7:7: = 252.
Neaiest disc-area constant in table under maxi-
iijum efficiency is 251 at pitch-ratio 1*0.
. • . Pitch = 15-5 feet.
The corresponding value of C, is 109.
20
. • . Revolutions = 109 X -rz-z, = 141.
15*5
Example 3. — Find the pitch-ratio and efficiency
of a screw for a vessel of 20 knots speed and 6000
EXPERIMENTS WITH MODELS. 71
l.H.P. The diameter to be 15 '5 feet and the
revolutions about 80 per minute.
Disc-area = 189 feet.
^^ = ^^^ ^ 6000 = 2^2-
Cb = 80 X 1^^^ = 62.
The nearest constants in table are at pitch-ratio
2'2 and efficiency 68 per cent. Where the
diameter and revolutions are both limited, the
curves on Plate 3 will probably be found more
convenient, as intermediate pitch-ratios can be
selected.
Example 4. — Find the diameter and pitch of a
screw to work at maximum efficiency for a vessel
of 20 knots speed and 6000 l.H.P. Revolutions to
be 85. Wake correction to be made for a form of
the fulness of H.M.S. Devastation^ corresponding
to a wake percentage of 15 • 8.
The multiplier from Table II. is 0-942.
20 X 0-942 = 18-8 knots.
By trial and error it will be readily found that
the constants 306 and 85 for disc-area and revo-
lutions respectively, at 1*3 pitch-ratio, will give
the required number of revolutions, thus : —
306 X 77rt-i^ = 276 square feet. . • . D = 18-75 feet
(18 •8)'
and
18-8
85 X - ,, „^ = 85 revolutions nearly.
18-75 ''
72 MARINE PROPELLERS.
Example 5. — Find the diameter, pitch, and
revolutions of a three-bladed screw to work at
maximum efficiency for a vessel of 20 knots speed
and 6000 I.H.P. Pitch-ratio to be 1 • 2.
C^ = 288. Cb = 92.
6000 LH.P. X ^-^ = 6940.
288 X ^^ = 260 square feet . • . D xs 17-8 feet.
20*
92 X j|?3 = 103 revolutions.
Pitch =(7-8 X 1-2 = 21-3 foot
=:
c*
B
C.
Ck
Ci
c.
e.|c.
c. i c.
^-.
C„
"i
0.
0-80
4fi8 1
22
30*
128
215
134
157
142
m
150
17
160
6S
m
0-QO
506 'l
0!)
329
114
234
120
170
127
125
135
93
144
71
154
1-011
S16
99
355
104
251
100
1«4
tl£
135
123
100
131
76
HO
1-10
5S5
91
380
93
270
100
196
105
144
IJ3
107
120
S2 J 128
1-20
625
83
405
87
288
»2
210
97
154
104
115
111
87!n9
1-30
065
77
431
81
306
85
224
91
163
97
122
103
93 Itl
1-40
70*
72
456
7?
325
SO
230
85
173
00
129
97
98
104
1-50
742
67
4N2
71
342
75
250
73
183
85
136
91
104
98
1-60
1-70
780
O'i
507
533
07
63
378
71
67
263
276
75
71
193
202
60
76
144
151
«7
«2
109
115
93
1-80
5S8
60
3S6
64
SOO
68
212
73
159
78
120
84
1-90
584
57
415
61
304
63
322
69
166
75
125
81
2'00
609
55
432
58
315
62
231
67
173
72
131
77
2' 10
635
62
450
56
329
59
241
64
180
ti!)
136
75
2-20
6(10
50
466
54
342
67
250
62
187
67
142
72
2-30
685
48
•186
52
355
65
260
59
I'M
i-A
H8
69
2-40
710
47
505
50
369
53
270
57
202
62
153
67
2-50
730
45
523
48
-
52
280
56
209
60
169
65
6c«Ie oF AbBclBta ralne.
(Bpeediofcoot*)*'
8 "
ii!»^-^
• P/uiJii«wv Shif
-^
{0^90 )
-BELTeO MeRSKY.ro*««s;
"i
i:
• ADMIRAL CLASS. fo-S««;
r
ITAUA.ro-5««;
-i — CONQUEROR .roMi )
#■
T
JCRBAT EASTERN . fo't)
(WITH TWIN SCREWS.
- DEVASTATION . (o-Mi)
'DUIU0,(0'61T)
.FUU'vo GioJcL. (oS2€)
Warrior. A-fn-rtit^Oi^trrn 1**5 j
Cntitu. EnoruiUf, ^f^po^ •
INFLEXIBLE. <o *??.;.)
it*
( 75
CHAPTER V.
GEOMETRY OP THE gCREW,
If a point move on the surface of a cylinder in
such a way that, while moving uniformly around
the cylinder it advances uniformly in the direction
of its axis, it will trace a curve known as the
helix. Imagine the cylinder cut on one side by a
straight line parallel to the axis meeting the helix
in consecutive points A C (Fig. 27), and then
imroUed and laid flat, the circumference through
A will become the straight line A B ; B C at
right-angles to it will represent the direction of the
axis while that part of the helix formed during a
complete revolution of the tracing point will be
represented by the line A C. Since the distances
moved by the point in the directions A B, B C are
proportional, A C is a straight line. B C being
the distance moved through in the direction of the
axis, while the point goes once entirely round the
cylinder, is the pitch, while the angle BAG, which
the unrolled helix makes with a plane at right-
angles to the axis, is the angle of tlie helix or
screw.
If a straight line move uniformly round an axis
which it intersects, and to which it is always at
76
MARINE PROPELLERS.
right angles, advancing at the same time uniformly
in the direction of the axis, it will sweep out a
surface known as a helicoid, and every point in
the generating line will trace a helix as described
FiQ. 27.
above, necessarily lying on this helicoid. Since,
during a complete revolution of the generating
line every point moves through the same distance
in the direction of the axis, the helicoid is a surface
of uniform pitch, that is B C, Fig. 27, is constant
for the helices traced by all points in the generating
line. A helicoid can therefore be, and often is,
used for the acting face of a screw-blade of uniform
pitch. It is not necessary, however, that the gene-
rating line should be at right angles to the axis ;
such a surface may be generated by any line,
straight or curved, moving uniformly along and
revolving uniformly around an axis, intersecting
and always making the same angle with it.
The helix traced by any point in the gene-
GEOMETRY OF THE SCREW, 11
rating line will also be the curve of intersection
with the screw surface of a co-axial cylinder of
radius equal to the perpendicular distance of
the point from the axis. The larger the radius
of the cylinder, the larger of course the length
of the circumference, as A' B, Fig. 27, and as
the pitch is constant, it follows that the angla
of the helix must ^^^t'^^a^^ Qfl ^^^^ radius of th(
inters ectinpj' cylinder innrftimpig. We thus arrive
at the fundamental geometrical property of a
surface of uniform pitch, viz. : — Co-axial cylin-
ders intersect it in helices, all of which have the
same pitch, but whose angles vary, decreasing
as the radius of the cylinder increases. Near
the axis, therefore, the helices will approximate
in direction to that of the axis, and as the dis-
tance from the axis increases, they will lie more
and more at right angles to it. If 6 be the angle
of the helix, p the pitch, and r the radius of the
P
intersecting cylinder, tan = « •
The curve of intersection of a co-axial cylinder
with a screw surface will hereafter be referred to
briefly as the ** curve of intersection," or the
"helix of intersection."
In commencing the design of a propeller for a
given ship, the diameter and pitch must be first
decided, and the considerations which will deter-
mine these having been fully dealt with in the
preceding chapter it is only necessary to say that
78 MARINE PROPELLERS.
it is usual to provide for an immersion of the tip
of the upper blade equal to about y^^ the diameter
of the propeller, and to allow a clearance from
the ship's side varying from 6 inches in small
ships to 1 foot in large ones.
With regard to the number of blades to be used,
if the necessary disc-area can be obtained with a
three-bladed propeller it is to be preferred, but
if the draught of water is limited, a four-bladed
propeller is practically equivalent to a three-bladed
one of rather larger diameter.
The expanded blade-area of the Admiralty
standard blade is an ellipse of major axis equal
to the radius of the propeller, and of minor axis
equal to -^^ the major axis. It is often found,
however, that owing to the diameter being limited,
sufficient blade-area is not obtainable by these
proportions; in such cases the elliptical form is
adhered to with an increased minor axis of from
•5 to '55 the major.
If sufficient area cannot thus be obtained even
with four blades, as in the case of shallow draught
vessels where the diameter is very limited, the
elliptical form may be greatly departed from, and
the blade widened at the tip. A boss of diameter
- diameter of propeller .„ _
equal to gi fQ 3 1 w^H cut away about
^ the area of the standard ellipse.
The expanded blade-area, which may be de-
scribed as a flat surface of approximately equiva-
GEOMETRY OF THE SCREW. 79
lent area to that of the blades, both as to amount
and disposition, is derived as follows : —
A co-axial cylinder will intersect the screw
surface in a helical curve making a certain angle
with the axis, and it will intersect a plane passing
through that diameter of the cylinder which passes
through the middle point of the helical curve, and
making the same angle with the axis in an elliptical
arc. The length of the screw being small com-
pared with the pitch, these two arcs will nearly
coincide, and no great error will be involved by
assuming that they do coincide. Imagine these
elliptical arcs at all radii to be swung round a
common centre line till they all lie in the same
plane with their major and minor axes respectively
coincident (though necessarily of diflFerent length),
then the curve passing through their extremities
will form the boundary of the expanded blade-
area. This area is very nearly equal to the actual
whole surface of the acting face of the blade, being
in fact, somewhat less than it.
To draw a right-handed uniform pitch screw of
Admiralty or Griffiths type, with elliptical blades
of standard form, with generating line at right
angles to the axis, with axis horizontal and centre
line of blade upright : —
Draw a straight line A B, Fig. 28, Plate 3, to
represent the axis of the propeller, and B C at
right angles to it equal to the radius of the pro-
peller. With B C as major axis and minor axis
80 MARINE PROPELLERS.
equal to -j^ of B 0, describe the ellipse B D E.
Draw the circle F H G of radius equal to that ot
the boss, cutting the ellipse in FQ-, the area
GDCEFHG is the expanded area. Divide
H into a number of parts, preferably equals at
the points a, 6, c, rf, e, /. If p be the constant
pitch of the propeller, take B A equal to -^ and
join A H, Aa, A6, Ac, &c., these lines are called
the pitch-lines. Then since the tangent of the
angle which any one of these lines passing through
a point on B C distant r from B, makes with B is
o , these angles are the angles of the corre-
sponding helices of intersection, and, therefore, by
the assumption previously explained, they are the
angles which the planes of the elliptical arcs form-
ing the expanded area make with the plane at
right angles to the axis of the propeller when the
arcs approximately coincide with the correspond-
ing helices on the actual blade. Consider that
elliptical arc on the expanded area passing through
Cy Be is its semi-minor axis, and since the angle
c A B is its inclination when lying in its position
on the actual blade to the axis of the intersecting
cylinder, c A must be the length of its semi-major
axis.^ Similarly AH, Aa, A6, &c., are the lengths of
the semi-major axes of the elliptical arcs through
H, a, ft, (fee, respectively, and B H, Ba, (fee, are the
corresponding semi-minor axes. It follows at once
GEOMETRY OF THE SCREW, 81
that A is a focus of all these elliptical arcs, the other
focus being at K where B K = B A. Draw, there-
fore, through the points H, a, h^ &c., elliptical arcs
with foci A, K and semi-major axes respectively
equal to All, Aa, A6, &c. Then by the assump-
tion, these elliptical arcs represent the helical arcs
of intersection turned about B C till they lie in the
same plane. If we reverse the process and turn
them back from the expanded area through the
same angle, their extremities will give us points
on the outline of the blade. The angle any
particular arc must be turned through is that
which its pitch-line makes with B A.
This enables us to draw the projections, and in
dealing with these we shall take a particular one
of the elliptical arcs and show how to obtain the
projections of the point at one of its extremities ;
tlie projections of the other extremity may be
obtained in a similar way, but on the other side
of the centre line. This will be a specimen arc.
If the same method be adopted for the extremities
of all the other arcs, series of points will be
obtained, and if fair curves be drawn through
the respective series, we have the required pro-
jections. For each projection of the blade we
shall therefore deal only with the projection of
one .point on its outline.
Take any one of the elliptical arcs as the speci-
men, say that through c, viz. c, c Ca, Fig. 28, Plate 3.
Draw C2 Co, parallel to the axis, mark off on the
a
82 MABINE PROPELLEBS.
pitch-line through c, c CJg = ^o ^j- Draw c^ c^ per-
pendicular to A B and c c^ parallel to it. Then
CC4, is the projection of CqC2 on a fore and aft
plane, and C3C4 is its projection on an athwartship
plane. Set off CqC^ = C3C4, then ^5 is a point on
the athwartship projection of the blade. Similarly
on the other side of the arc we get another point
c^j and so on for all the other arcs.
It may be noticed that this projection may also
be found thus; draw circular arcs with B as
centre through H, «, ft, c, &c. On the blade the
elliptical arc approximately coinciding with the
helical arc will project on an athwartship plane
into a circular arc, the chord of the- former of
course projecting in that of the latter. Dealing
with the arc through c, draw Co c^ parallel to the
axis through Ca, meeting the circular arc in C5, then
the elliptical arc c c^ will project on an athwart-
ship plane into the circular arc c Cg. c^ is there-
fore a point on the athwartship projection of the
blade.
For the fore and aft projection take K P, Fig. 29,
as the axis of the propeller, and draw P Q at right
angles to it. Set off distances P H7, Pa^, P67, &c.,
respectively, equal to B Ho, Bag, Big, &c., and draw
straight lines through the points H,, ay, &7, &c.,
parallel to K P. Dealing with the line c^ ۥ, Cg,
set off CtCs equal to cc^j Fig. 28, then Cg is a
point on the fore and aft projection of the blade.
Similarly for other points.
GEOMETRY OF THE SCREW, 83
For tlie liorizoutal projection take N R, Fig. 30,
as the axis, R being forward, and draw straight
lines through N making angles with N R equal to
H \ B, a A B, &c., Fig. 28, and inclining as
shown since the blade is right-handed. These
straight lines represent the directions on the actual
blade of the chords of the ellij^tical arcs, the
lengths are given in Fig. 28. Dealing with the
line Nc*', which is the direction of the chord ^0^2*
Fig. 28, mark off Ny = c^c^. Fig. 28, then y is a
point on the horizontal projection. On the other
side of N we get similarly y', the horizontal pro-
jection of tlie other extremity of tlie chord. Simi-
larly for other points.
The complete projections of a three-bladed
propeller are shown in Figs. 33, 34, 35, Plate 4.
The athwartship projections of the two lower
blades are simply repetitions of that of the upper
blade, their centre lines being inclined to that of
the upper one 5it angles of 120°, Fig. 33.
The fore and aft projection of the lower blade.
Fig. 34, is obtained thus : — Across the projections
of the blades in Fig. 33 and the top blade of
Fig. 34 draw straight lines at right-angles to their
centre lines as in Figs. 28 and 29. Consider the
point whose athwartship projection is c^ on the
right-hand lower blade. Fig. 33 ; this being on the
following edge will be abaft the centre line in
Fig. 34, the corresponding point on the leading
edge (ci) appearing on the forward side.
G 2
81 MARINE PROPELLERS,
Then to obtain the position of this point on the
fore and aft projection it must be borne in mind
that it must lie in the same vertical plane perpen-
dicular to the axis as it does when the blade is
upright, and at the same distance from the hori-
zontal plane through the axis as in it& athwartship
projection.
Consider the point whose athwartship projection
is t?2, Fig. 33. Draw C3C4, Fig. 34, on the left-hand
side of the centre line P Q, parallel to the axis, at
the same distance from it as Cj, Fig. 33, is from
B P. Take c^c^ equal to CoC-t (c^ being the
position on the fore and aft projection which the
point would occupy if the blade were upright),
then C4 is a point on the fore and aft projection of
the right-hand lower blade. Similarly for other
points.
Proceed in a similar manner for the other lower
blade, bearing in mind that the upper edge,
Fig. 33, is here the leading or forward edge. The
projection of one blade only is shown in Fig. 34
to avoid confusion.
In the horizontal projection of the lower blades.
Fig. 35, we proceed similarly. The point whose
athwartship projection is t?2, Fig. 33, for example,
will appear on the after side of the centre line of
the blade at a distance from it equal to CoCj,
Fig. 34; and from the axis equal to the perpen-
dicular distance of ("a* Fig. 33, from B E.
The projections of a three-bladed propeller are
OEOMETRT OF THE SCREW,
85
thus completely determined. It may be remarked
that it is often considered sufficient to replace the
elliptical arcs on the expanded area, Fig. 28, by
circular arcs with B as centre, forming the pro-
jections from the chords of these arcs precisely as
has been described for the elliptical ones. The
error introduced by this method of procedure is
not great, being only appreciable towards the root
of the blade, where it is of little consequence.
Blades are sometimes made with the generating
line inclined to the iaxis, or in technical terms they
are made with a skew.
Let the two straight lines,
AB, AC, Fig. 36, the
former at right-angles
to an axis, the latter
inclined to A B at an
angle a, moving together,
generate screw surfaces
of uniform and equal
pitch. Then the helices
of intersection of these
two surfaces will be ex-
actly similar, and one will be always a constant dis-
tance from the other, this distance being at a radius
Vj r tan a. Imagine these two surfaces so far
similar, that when A C at any radius leaves the
surface, A B at the same radius leaves its surface,
then the expanded area of the surface so formed by
A B will represent what may be termed the eflfec-
86 MARINE PROPELLEBS.
tive expanded area of that formed by A C, and this
should be of the elliptical or other form which
would have been used if the generating line had
been at right-angles to the axis. A blade generated
by A C would therefore be formed from a blade
generated by A B, simply by setting the helices of
intersection, definite distances aft, the distance at
M for example being M N. It follows therefore
that the athwartsliip projection of the blade for the
same " eflFective " expanded area is independent of
the skew, and consequently for a skew blade with
effective expanded area as for the blades shown in
Figs. 33, 34, 35, the athwartsliip projection will
be as in Fig. 33, no matter what the skew be.
The fore and aft projection of tlie upper blade,
Fig. 37, will be formed by using a centre line
inclined to the vertical at an angle equal to the
inclination of the generating line to tlie vertical,
and proceeding as in Fig. 20, setting off the
distances horizontally. The projections of the
lower blades are determined in a similar way to
that described for Fig. 34. For example, the
point whose athwartsliip projection is c^, Fig. 33,
will appear on Fig. 37 at C4, lying in the same
vertical straight line as Ci {ct being the position
of this point when the blade is upright), and being
perpendicularly away from the axis, a distance
equal to that of C2 from the horizontal plane
through the axis.
Next consider the horizontal projections. Fig. 38,
GEOMETRY OF THE SCREW. 87
For the top blade the pitch-lines are not all drawn
through the same point as in Fig. 35, but each
line is drawn at the corresponding angle to the
axis through a point on the axis at a distance from
Ml Ni (corresponding to M N in Fig, 37), equal to
the distance of the corresponding point on the
generating line P Q from M N, Fig. 37, the pro-
cess then being as in Fig, 30. For the lower
blade we proceed as in Fig. 35, for instance, the
point (ca, Fig, 33) corresponding to C7, Fig, 37,
when the blade is upright, will appear in Fig. 38
at Cg at a distance from the axis equal to the
distance of Cj, Fig. 33, from the vertical plane
through the axis and from Mj Ni, equal to the
distance of c^ from M N, Fig. 37.
The projections of a three-bladed propeller with
skew blades are shown in Figs. 33, 37, 38, except
that the left-hand lower blade of Fig. 33 has not
been shown in Fig. 37 to avoid confusion.
Where the generating line is curved, the method
is now obvious.
Wo pass on to consider blades not of uniform
pitch.
If it is desired to make the pitch increase from
the root of the blade towards the tip, that is, if the
pitch at c. Fig. 28, for example, be 2 ttB Z instead
of 2 TT B A, then the pitch-line at c will be Z c:
instead of A c. With this modification the method
of constructing the projections is the same.
Blades are frequently made with an increasing
88
MARINE PROPELLERS.
pitch from leading to following edge. In Fig, 39,
let the pitch at the leading edge at a radius equal
c b
be a 6, and suppose as we go to a point rf,
to
TT
the pitch increases to b e, then e c b will be the
pitch-angle at this point. Similarly if at / the
Fig. 30. "
pitch increases to t(/, then bc(/ is the pitch-angle
at/. Draw dh parallel to c^, and fk parallel to
cg^ then if the curve of intersection at the radius
under consideration be unrolled as in Fig. 27,
instead of being straight it will be as adf—in
other words, the pitch-line through a will not be
straight ; if the pitch varies continually, then the
pitch-line will be a continuous curve.
A blade of uniformly varying pitch from lead-
ing to following edge would be generated by a
line always intersecting, and always inclined at
the same angle to the axis, moving uniformly
GEOMETRY OF THE SCREW. 89
round the axis while advancing with uniform
acceleration along it.
Only the acting face of the blade preserves the
helical form, the back being made to give the
required thickness at the difiFerent parts. The thick-
ness at the centre line of the blade is first fixed at
root and tip, and set off from the face of the blade.
The two points thus found being joined, the dis-
tance of this line from the face gives the thickness
at any intermediate point (see Fig. 29). The thick-
ness at the tip should be as small as possible, con-
sistent with good casting or forging, as the case
may be, and in gun-metal is generally made about
-^^ inch per foot of diameter. The blade when
acting on the water is in the position of a beam
under a load distributed all over its surface,
varying in intensity, but it would be very difficult
to find the bending moment at the root, and it is
usual to make the rough assumptions that the total
pressure on the blade tending to break it about the
root section is proportional to the indicated thrust
P
or to —Ty
p K
(where P = I.H.P. per blade ;
p = the pitch of the propeller ;
R = the revolutions per minute),
also that the " leverage '* is proportional to D — rf,
D being the diameter of the propeller, and d that
of the boss ; and that the moment of inertia of the
root section of breadth h and depth h is propor-
90 MARINE PROPELLERS,
tional to b h^, then h the required thickness at the
middle of the root is obtained from the formula
p . 11 . h
the value of the coefficient c being about 230 for
gun-metal, and 90 to 100 for forged steel blades.
(In the above formula, /?, D, and d are to be
taken in feet, and b and h in inches.)
It is then usual to unroll the elliptical arc of
Fig. 28 at any radius into a straight line, set off
the thickness as found at its middle point, and
describe a circular arc through the point so found
and the extremities of the unrolled ellipse, and so
obtain the thickness at other points than the
middle (see Fig. 32).
When tlje blades are made separate from the
boss they are usually attached to it by bolts
arranged in a bolt circle of diameter C inches.
As the thickness of the metal at the root is not
disposed symmetrically about the centre of the
flange, it is convenient to put one more bolt on
the after side than on the forward side, and as
the after bolts take the ahead load, which is
greater than the astern, it is also an advantageous
arrangement. If B be the combined aiea in
square inches of the bolts at the smallcist section
(at the bottom of the thread) on tlie after side
of the blade, k the distance of the c*entre of
pressure of the blade from the under side of the
GEOMETRY OF THE SCREW.
91
flange in feet, R and P being as before, then
B = ~7w5~' tli® coefficient K ranging in value
from 18 to 21 for gun-metal.
The number of bolts having been settled, their
diameter is at once found. The bolts on the for-
ward side are usually made of the same diameter
for convenience. For the sake of possible adjust-
ments that may be desirable on the trials of the
machinery, and also for fining the pitch when it
becomes necessary to reduce the steam pressure in
the boilers, it is customary to make the bolt-holes
in the blade-flange oval in order that the inclina-
lion of the blades to the axis may be altered. The
amount of the oval is determined thus. Fig. 40.
Fig. 40.
D E
Let the true pitch of the blade be 2 tt C E, and let
the desired range of pitch be 2 tt E B and 2 tt E D
respectively, on each side of this pitch. Take a
92 MARINE PROPELLERS.
radius C A, so that A is about half-way up the
Uade. Join A D, AE, A B, tlien if ^ be the angle
DAB, the holes in the flange must be so elongated
as to admit of the blade being turned through ^
on each side.
The amount of the elongation on each side is
therefore ^n) ' f = '^^^' ^ being measured in
degrees.
If the axis of the helices of intersection of the
blade be originally that of the propeller shaft,
the acting surface will not be truly helical about the
centre line of the shaft when the blade is turned
round as just described, as the pitch is not altered
uniformly. There are only two sections of the
blade which receive the same change of pitch, and
tlicse are situated at the radii corresponding to a
pitch angle of 45° in the case of the original and
modified pitches respectively. Sections between
these points receive a less change of pitch, and
sections outside them a greater, in proportion to
their distance from them. The effect produced
therefore by twisting through any given angle
depends upon the pitch-ratio ; if this is small the
critical points are near the boss, and twisting
to augment pitcli for example causes the pitch to
increase throughout the greater part of the length
of blade, the maximum occurring at the tip. If
the pitcli-ratio be such tliat the critical points fall
GEOMETRY OF TUB SCREW, 93
about the middle of tbe length, twisting to fine
pitch will then result in a blade having the maxi-
mum pitch in the centre.
Figs. 29 and 31 show respectively longitudinal
and transverse sections through tlie propeller boss.
94 MARINE PROPELLERS.
CHAPTER VI.
THE HYDRAULIC PROPELLER.
There are many reasons why a hydraulic propeller
would be preferred to a screw or paddle in certain
cases, if an economical result could be obtained
with it, but tlie efficiency of the apparatus is
necessarily so small that at the present moment it
is believed that there is not a single vessel using
the propeller for warlike or commercial purposes.
When economy is a secondary consideration, and
the circumstances are such as apparently to pre-
clude the use of any propeller external to the
vessel, the hydraulic propeller finds its opportunity.
A steam lifeboat which has been recently built by
Messrs. li. and H. G-reen of Blackwall for the
National Lifeboat Institution, has been fitted with
hydraulic machinery, made by Messrs. J. I. Thorny-
croft and Co., and she has met with a considerable
measure of success. It was considered that the
difficulty of keeping a screw immersed, and the
danger of its becoming fouled by wreckage, or
injured upon a sandbank, rendered it unsuitable,
and justified the introduction of a propeller which
could never race, and which was much less liable
to injury.
THE IIYDBAULIC PROPELLER.
95
The term jet-propeller, although in common use,
is incorrect, the propeller in this system of pro-
pulsion consisting of a pump within the vessel,
which discharges jets of water in a stern ward
direction, which are analogous to the race of a
paddle or screw.
In 18'<9 a hydraulic vessel called the Ilydro-
motar was built in Germany from the designs of
Dr. Fleischer. In this vessel the engine and
pump were combined, the arrangement being as
follows : —
There was a cylinder lined inside with wood, at
the bottom of which was a large pipe leading to a
nozzle at the bottom of the vessel. A float of
nearly the same diameter as the cylinder worked
up and down in it. The cylinder being full of
water and the float consequently at the top, steam
was admitted by a valve above the float, and driv-
ing it down ejected the water through the nozzle
Fig. 41. On reaching the
bottom of its stroke, the
float opened the exhaust,
and the steam passed
into the condenser. The
vacuum then created in
the cylinder caused the
water to rise partly
through the nozzle, but
principally through a suction-valve in the bottom
of the condenser. The cylinder was thus filled
Fig. 41.
dQ
^
ZJ =^
VI]
96 MARINE PROPELLERS.
with water, and the float rose to the top, in
doing which it closed the exhaust and opened
the steam-valve, and the operation was re-
peated. The loss by condensation appears to
have been less than might have been expected in a
cylinder filled alternately with steam and water,
but as the cylinder was not entirely emptied at
each stroke, a layer of boiling water always re-
mained at the top and adhered to the wooden
linings as the float descended. The information
published is unreliable as no proper raeasnrt;d mile
trials were made. All calculations made from
indicated horsepower cards are of little value in
this system, as the loss between the boiler and the
indicator, which must be very large, is thereby
ignored. The only correct basis for comparison
with either a screw or a turbine would be the
amount of steam consumed per unit of work done.
In 18CG, two armoured gunboats, the Viper and
Watur^ntch, were built, the former being propelled
TEE HTDRAULJC PROPELLBS.
97
by twin screws, and the latter by hydraalic
machinery, designed by Mr. Ruthven. The
Watenmtclta propeller consisted of a turbine
14 feet indiameter, which drew water in at the
bottom of the vessel, and discharged it through
two 24rinch nozzles at the sides level with the
water (see Figs. 42 and 43).
In 1878, a hydraulic vessel was built by the
Swedish Government for competition with a simi-
lar vessel with twin screws. The hydraulic vessel
98
MARINE PROPELLERS.
was propelled by two turbines about 2 feet in
diameter, which discharged water through sub-
merged orifices at the sides near the extremities
(see Figs. 44, 45, and 46).
Fio. 45.
Fio. 46.
In 1883, Messrs. Thornycroft fitted one of a
number of second class torpedo boats they were
building for the British Admiralty with a hydraulic
propeller consisting of a turbine 2 feet 6 inches in
diameter, which discharged through two 9-inch
THE HYDRAULIC PROPELLER.
99
nozzles at the sides above water (see Figs. 47 and
48 and Plate 5), All these vessels were fully
Fig. 47.
Fio. 48.
described by the author in a paper read before the
Institution of Civil Engineers,* from which the
* Proo. Inat. Civil Enginoors, Ixxvii. p. 1.
II 2
100 MARINE PROPELLERS,
figures and Tables III. and IV., p. 104, giving a
detailed comparison of the performance of the
respective screw and turbine vessels, are taken.
In every case a very notable difference was found
between them, and always to the disadvantage of
the latter. There appears to be a loss of power
corresponding to about 50 per cent, experienced by
the hydraulic propeller as compared with the screw.
The causes of this loss are not hard to find.
In the case of the Water witch and the Swedish
boat, the water was received into the ship through
a hole in the bottom in such a way as to suddenly
arrest all the velocity which it had relatively to
the vessel. In other words the entering water
struck the ship and had the velocity of the ship
impressed upon it before it entered the turbine. If
the inlet is formed in the shape of a scoop, as was
done in the Thornycroft boat (see Fig. 47) and
Plate 5), and the water caused to change its direc-
tion gradually without having its velocity relatively
to the ship checked, then this cause of loss is
avoided. In such a case, if the vessel were towed
along with the turbine removed and replaced by
a curved channel connecting the inlets and outlets,
the water would be scooped up, and would flow out
at the nozzles, leaving tbem, if they are not above
the surface, with a velocity relative to the ship
equal to the speed of the ship, and with no
velocity relative to still water except such as would
be imparted by the friction of the passages.
THE nYDRAULIC PROPELLER. 101
The inlet of the Swedish vessel was subse-
quently altered as shown in thick black lines in
Fig. 44, and the partial scoop thus formed caused
an increase of speed from 7 '87 knots to 8*12
knots, with the same expenditure of power.
Another loss of efficiency in the hydraulic system
is due to the small area of stream acted upon, and
the consequently high velocity which has to be
imparted to it in order to give the necessary re-
action (see p. 4). The reason why the area of stream
acted upon is necessarily small, is that the size of
the orifice which it is possible to make in a ship's
bottom, is restricted by structural considerations,
and must be very small indeed compared to the
area of a screw's disc. Then again, the weight of
water admitted into the ship is a serious considera-
tion, as it represents so much loss of displacement.
A further waste of power is caused by the
friction of the water in the pipes and passages,
and by the changes in direction of its flow in
passing through the bottom and out through the
sides in a fore and aft direction. For these reasons
the hydraulic propeller is essentially wasteful. In
the screw and turbine competitive Thornycroft
torpedo boats, the efficiencies were found to be as
follows:— Screw boat : engine, 0*77; screw pro-
peller, • 65 ; total efficiency, • 5. Hydraulic
boat : engine, 0*77; pump, 0*46; jet, 0*71;
total efficiency, ' 254.
The efficiencies of the pump and jet in this boat
102 MARINE PROPELLERS.
were measured by the author in the following
manner : —
A thin plate 1^ inch square was attached to
the end of a thin lever and placed in the jet just
where it left the nozzle. The pressure on this
plate was recorded by a dynamometer attached to
the end of the lever. By finding the pressure
upon a similar lever without the plate, the eflFect of
the portion of the lever immersed in the jet could
be allowed for. The apparatus was so arranged
that the pressure could be measured at every point
of the jet and not in the centre only. From the
pressures on the plate the velocity of the stream at
diflFerent parts of the jet was estimated, and from
the mean velocity, the quantity of water discharged
was calculated.
The relation between velocity of jet and pressure
on the plate is as follows : —
ProBSTire on plate
• 627 X (area) x heaviness of fluid x (velocity)^
gravity
If W = weight of water discharged per
second ;
V = speed of vessel in feet per second ;
S = true slip or acceleration, or addi-
tional velocity impressed by the
propelling apparatus in feet per
second;
V + S = velocity of discharge in feet per
second ;
THE HYDRAULIC PROPELLER. 103
g = acceleration produced by gravity
in feet per second = 32*2;
V
Then the theoretical efficiency of the jet = =.
Efficiency of pump, supposing jet to have theo-
retical efficiency and the engine an efficiency of
0-77;
Work stored up in water
Effective H.P, of engine "
Efficiency of pump and jet
Useful work in jet
Effective H.P of engine
Total efficiency
Useful work in jet
wvs
9
WS«
2?
I.H.P. X 650
X 0-77
WVS
1
9
LH.P. X 550
xO-77
WVS
9
Work expended LH.P. x 650
104
MARINE PROPELLERS.
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CHAPTER VII.
THE SCREW-TURBINE PROPELLER.
This propeller was the fruit of the study given to
the subject of hydraulic propulsion by Mr. Thorny-
croft, when designing the hydraulic torpedo boat
already mentioned.
It has been pointed out in the preceding chapter
that there are four characteristics of the centri-
fugal pump as applied for the purpose of pro-
pelling vessels, which prevent it from competing
successfully with the paddle or the screw. These
are: —
1, The diificulty of getting the water through
the bottom of the vessel and into the pump without
checking the velocity it already has relative to the
vessel.
2. The necessity of carrying in the vessel all the
water acted upon.
3. The loss caused by friction of the water in
the pipes.
4, The loss due to bends in the passages.
It was obvious that if the turbine could be put
outside the vessel and under the bottom, the first
two causes of loss would be avoided, and also that
if the water could be made to flow axially through
106
MABINE PROPELLERS.
the turbine instead of radially as in the Ruthven
pump, no pipes would be needed, there would be
no loss by changes of direction, and the friction
would be reduced to that due to passage through
the turbine alone. The propeller illustrated in
Fig. 49 was therefore devised upon these lines,
Fig. 49.
and as it is neither a screw nor a turbine strictly
speaking, although allied to both, it has received
the name of the screw-turbine.
It consists of a cylinder containing within it a
body or boss of such a shape that the channel is
gradually contracted from the forward to the after
end. Within the forward part of the cylinder are
placed revolving screw-blades attached to the
forward part of the boss, which is in two portions.
The pitch of the forward edge of the screw-
blades multiplied by the number of revolutions is
approximately equal to the velocity of feed ; the
pitch increases uniformly along the length of the
blade, imparting a uniform acceleration to the
water. Aft of the revolving blades are placed
numerous fixed blades of contrary curvature. The
TEE 8CREW-TURBINE PROPELLEB. 107
area of the channel through the propeller is so
proportioned as to suit the acceleration of the water
caused by the blades. Thus at the forward end is
a large opening which will admit a certain quan-
tity of water at the velocity of feed ; at the after
end the area is restricted to that necessary to allow
of the exit of the water at the speed of discharge.
The long tapering body forming a prolongation of
the boss outside of the cylinder, allows the streams
of water to unite gradually without the formation
of eddies. As the long pitch of the screw-blades
causes considerable rotation of the water, the curved
guides are so formed as to direct the water into a
straight line aft, and the rotary motion is thus
utilised without loss. When a model of this pro
peller was experimented upon, the thrust of the
revolving blades was measured separately from the
thrust of the fixed guides. The latter was found
to be quite considerable, amounting in the case of
a very long pitch propeller to one-third of the
total thrust.
The efficiency of the screw-turbine was found by
experiment to be at least equal to that of the
common screw, and a given thrust can be obtained
with a much less diameter. It is therefore a very
suitable propeller for vessels of shallow draught.
As the water is not accelerated at all before it
reaches the propeller, that is, as there is no sucking
action, there would appear to be less augmentation
of hull resistance caused by the screw-turbine than
108 MABINE PROPELLERS.
by any form of open screw. It was stated on p, 21,
that all open propellers work in a stream having a
S
velocity varying between V + S and ^ + 9
depending upon the greater or less rotation of the
race, the eCFect of the guide-blades in combina-
tion with the enclosed and contracted channel is
to prevent rotation of the race, and to place the
screw-turbiue in the same condition as an open
propeller would be in if it were possible to imagine
one which, like Mr. Fronde's " Acuator," produced
no rotation. Its efficiency is therefore equal to
V
Q, and the loss of work is the least possible.
^2
Were it not for the large surface exposed to
friction, it might be expected to have a much
higher efficiency than the common screw.
It can be used with advantage, because of its
relatively small diameter, in sea-going vessels,
which often are in very light trim, and do not
then properly immerse a common propeller, and
therefore waste a large amount of power (see p. 34),
and also in vessels in which the draught of water is
so limited that the ordinary screw cannot be used.
In such cases the screw-turbine possesses advan-
tages as compared with paddle-wheels when high
speed is required, because the weight of the
machinery is much less than that of paddle engines
of the same power, which necessarily run slowly.
THE SCREW-TURBINE PROPELLER. 109
The arrangement shown in Plate 6 has
proved very successful when the draught of water
is small. The launch illustrated has a draught
of 12 inches. A tunnel is formed in the bottom
of the boat, the top of which rises above the sur-
face, the ends being submerged. A 16-inch screw-
turbine is placed in the tunnel, so that one-fourth
of the diameter of the propeller is above the water-
level when the boat is at rest, but as soon as it
moves, water is drawn up into the tunnel, and the
air expelled by the action of the propeller, which
then works completely submerged. There is no
loss of power in lifting the water 4 inches
above the level of the surface, because in falling
it gives out the work expended in raising it.
There is an incidental convenience in this ar-
rangement. An air-tight door can be placed at
the crown of the tunnel immediately over the
propeller, which can be opened from inside the
boat, since the admission of air to the tunnel
causes the water within it to fall to the level of the
outside water surface, and leaves the propeller
partially emerged. It can then be examined and
cleared if it should have become fouled, and if
there are twin screws this operation can be per-
formed upon one propeller while the other is
revolving slowly.
Some vessels 140 feet by 21 feet, and having a
draught of water of 1 foot 9 inches only, have
been built upon this plan by Messrs. Thorny croft.
110 MARINE PROPELLERS.
They were propelled by twin screw-turbines
32 inches diameter, and attained a speed of
15 i knots per hour. A launch 56 feet long and
16 inches draught of water has attained a speed
of 16^ knots with one screw-turbine 20 inches in
diameter.
A smaller draught of water can be obtained
by the use of this propeller than would be possible
with the hydraulic propeller, on account of the
excessive weight demanded by the latter for
machinery and water.
INDEX,
A.
Air in screw race, 25, 34, 38
AlectOy H.M.S., 6
Antispire, 30
Apparent slip, 14
Archimedes, 25
Auxiliary screws, 45
B.
Balancing screws, 35
Bergen, 32
Bevis screw, 45
Blade area, 14, 65, 66, 78
Blnff stem, effect of, 33
British Association Beport on steering, 40
C.
Cargo steamers, screws for, 67
Centrifugal action of screws, 25
Collingwood^B screws, 16
Constants for disc-area, 58
Table of, 73
Curves of efficiency, 57
D.
Dead water, 33
Definitions, 12
Diso-area, constants, 59, 73
„ „ definition, 14
Dundonald's screw, 25
Dynamometer used in experiments, 55
112 INDEX.
E.
Efficiency, affected by pitch-ratio, 61
„ „ slip-ratio, 51
„ causes of loss of, 4
limitatioDS of, 3
of hydraulic propeller, 101, 104
Electric launches, screws for, 47
F.
Feathering screws, Bevis, 45
Griffiths, 34
White, 42
FitzGerald's theory, 2
Flat-bladed screws, 45
Fleischer's Hydromotor^ 95
»> »»
a.
GreenhiU's theory, 2
Griffiths screw, 26
„ self-adjusting screw, 34
„ self-governing screw, 26
Guide-blades, 28, 107
H.
Ilirsch screw, 27
Howell torpedo screws, 47
Hydraulic propeller, 4, 94
HydromotoTj 95
I.
Immersion of screus, 25, 34, 78
Inclined shaft, effect of, 35
Increasing pitch, 13
J.
Jet propeller, see Hydraulic propeller.
INDEX, 113
Ii.
Lateral motiou of storn caused by screw, 38
,9 „ „ resisted by screw, 41
LcDgtli of blade, 12
Loss of efficiency, causes of, 4
M.
Mangin's screw, 27
Models, how to make, 53
N.
Negative slip, 15, 64
O.
Oar efficiency, 3
Overlai)ping screws, 47
P.
Paddle-wheels, 6
Phant'^m ship, 58
„ engine, 58
Pitch, definition, 12
„ how to estimate at sight, 24
„ measurement of, 22
„ virtual, 35
Pitchometer, 21
Position of screws, 32
rropellers, balancing, 35
Dundonald's, 25
feathering, 34, 42, 45
Fleischer's hydraulic, 95
Griffiths', 26, 34
guide-blade, 28, 107
„ Hirsch's, 27
„ hydraulic, 94
„ Mapgin's, 27
«9
>»
«>
9*
114 INDEX.
Propellers, model, 51
Rigg's, 28
screw-turbine, 106
Thomycroft's, 29
Woodcroft's, 13
»»
»»
i»
»»
B.
Hacing, 37, 40
Rankine's theory of propellers, 2, 3
BatOer, 6
Reaction, 1
Reversing engines, effect of, 40
Revolutions, average of paddle-wheels, 9
Rigg's propeller, 28
Rotatory motion of wake, 2, 21
Rudder, twisted form of, 28
8.
Screw, sec Propeller
Screw-turbine, 3, 105
Shallow-draught steamers, lOD
Slip, apparent, 14
„ formula for, 15, 04
„ negative, 15
„ of paddle-wheels, 9
„ real, 1
Steering, effect of screws on, 38
„ propeller, 42
T.
Teutonic's screws, 48
Thorny croft's common screw, 20
„ screw- turbine, 105
Torpedo, screws for, 47
Triple screws, 49
Twin screws, 47
Twisting blades in boss, CI, 02
Tugs, screws for, 46
INDEX. 115
»» »>
»» »>
V.
Varying pitch, 13, 16, 23, 27, 29, 87
Vibration caused by inclined shaft, 37
unequal speed of wake, 34
turning, 41
Viper, 96, 104
Vortex theory, FitzGerald's, 3
W.
Wake correction, 58
„ speed of, 33, 38
„ values of, 74
Watemiich, 96, 104
White's feathering screw, 42
Woodcroft's screw, 13
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■ i897-
BOOKS RELATING
TO
Applied Science
PUBLISHED BY
E. & F. N. SPON, LIMITED
LONDON: 123 STRAND.
NEW YORK : SPON & CHAMBERLAIN.
Algebra. — Algebra Self-Taught. By W. P. Higgs,
M.A., D.Sc, LL.O., Assoc. Inst C.E., Author of 'A Handbook of the
Differential Calculus,,' etc. Second edition, crown 8vo, cloth, 2s, 6d.
CONTENTS :
Symbols and the Signs of Operation-— The Equation and the Unknown Quantity-
Positive and Negative Quantities — Multiplication — Involution— Exponents — Negative Expo-
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Common i Logarithms— Compound Multiplication and the Binomisd Theorem— Division,
Fractions, and Ratio— Continued Proportion— T&e Series and the Summadon of the Series-
Limit of Series— Square and Cube Roots— Equations— List of Formulae, etc
Architects' Handbook. — A Handbook of For-
muia^ Tables and Memoranda^ for Architectural Surveyors and others
engaged in Building, By J. T. HuRST, C.E. Fourteenth edition, royal
32mo, roan, 5^.
" It is no dbparas|ement to the many excellent publicadons we refer to, to say that in our
opinion this little poocet-book of Hurst's is the very best of them all, without any exception.
It would be useless to attempt a recapitulation of the contents, for it appears to contain almost
tverything that anyone connected with building could require, and, best of all, made up in a
compact form for carrying in the pocket, measuring only 5 in. by ^ in., and about f in. thick,
in a limp cover. We congratulate the author on the success of^hu laborious and practically
csmpiled litde book, which has received unoualified and deserved praise from every profes-
sional person to whom we have shown it."— The Dublin Builder.
Architecture. — The Seven Periods of English
Architecture^ defined and illustrated. By Edmund Sharpe, M.A.,
Architect. 20 steel engravings and 7 woodcuts^ third edition, royal 8vo,
cloth, 1 2 J. 6^.
A
1CATAL0GUE OF SCIENTIFIC BOOKS
Baths. — The Turkish Bath: its Design and Con-
struction for Public and Commercial Purposes. By R. O. Allsop,
Architect With plans and sections^ 8vo, cloth, 6x.
Baths and Wash Houses. — Public BatJis and
Wash Houses. By Robert Owen Allsop, Architect, Author of * The
Turkish Bath,' &c. With cuts and folding plates y demy 8vo, cloth, dr.
Belting. — Belt Driving. By George Halliday,
Whitworth Scholar. With plates^ 8vo, cloth, y. 6d.
CONTENTS :
Description of difTerent Kinds of Belts — Pressure transmitted by Belts— Length of Belt
and Conea Pulleys — Stretching of Belts — V Pulleys — Arms of Pulleys — Methods of Use of
the Belt discussed — Rope Gearing — ^Tables— Rules for finding the Pitch of Spur^Wheels.
Blasting. — Rock Blasting: a Practical Treatise on
the means employed in Blasting Rocks for Industrial Purposes. By
G. G. Andr£, F.G.S., Assoc. Inst C.E. With 56 illustrations and 12
plates^ 8vo, cloth, 5/.
Boilers. — A Pocket-Book for Boiler \Makers and
Steam UserSy comprising a variety of useful information for Employer
and Workman, Government Inspectors, Board of Trade Surveyors,
Engineers in charge of Works and Slips, Foremen of Manufactories,
and the general Steam-using Public. By Maurice John Sexton.
Fourth edition, enlarged, royal 32mo, roan, gilt edges, 5x.
Boilers. — The Boiler-Maker s & Iron Ship-Builders
Companion^ comprising a series of original and carefully calculated
tables, of the utmost utility to persons interested in the iron trades. By
James Foden, author of * Mechanical Tables,' etc. Second edition,
revised, with illustrations ^ crown 8vo, cloth, 5J.
Brass Founding. — The Practical Brass and Iron^
Founder^s Guide, a Treatise on the Art of Brass P'ounding, Moulding, the
Metals and their Alloys, etc. By James Larkin. New edition, revised
and greatly enlarged, crown 8vo, cloth, lar. 6d, net.
Breweries. — Breweries and Mattings : their Ar-
rangement, Construction, Machinery, and Plant. By G. Scamell,
F.R.I.B.A. Second edition, revised, enlarged, and partly rewritten. By
F. COLYER, M.I.C.E., M.I.M.E. With 20 plates, 8vo, cloth, 12s. 6d,
Bridges. — Elementary Theory and Calculation of
Iron Bridges and Roofs. By AUGUST RiTTER, Ph.D., Professor at the
Polytechnic School at Aix-la-Chapelle. Translated from the third
German edition, by H. R. S AN KEY, Capt. R.E. With 500 illustrations^
8vo, cloth, 15/.
PUBLISHED BY K & F. N. SPON, LIMITED. 3
Bridges. — Plate Girder Railway Bridges. By
Maurice Fitzmaurice, B.A., B.E., Mem. Inst. C.E. Plates^ 8vo,
cloth, 61. CONTENTS :
Formuiz and Tables of Loads and Weights for Plate Olrder Bridges, with Remarks on
the allowable Working Stresses to be adopted in Steel and Iron — The Market sizes of
Plates and Bar;», and the different kinds of Bridge floors, with examples worked out in
detaiL
Bridges. — Stresses in Girder and Roof Trusses
for both Dead and Uve Loads by Simple Multiplication^ with Stress
Constants for 100 cases, for the use of Civil and Mechanical Engineers,
Architects and Draughtsmen. By F. R. Johnson, Assoc. M. Inst. C.E.
Part I, Girders. Part 2, Roofs. In i vol., crown 8vo, cloth, 6j.
Builders' Price Book. — Spans* Architects' and
Builders' Price Book^ with useful Memoranda, By W. YoUNG. Crown
8vo, cloth, red edges, y, 6d, Published annually.
Building. — The Clerk of Works : a Vade-Mecum
for all engaged in the Superintendence of Building Operations. By G. G.
HOSKINS, F.R.I.B.A. Sixth edition, fcap. 8vo, cloth, is. 6d.
Building. — Tke Builders Clerk: a Guide to the
Management of a Builder's Business. By Thomas Bales. Fcap. 8vo,
cloth, I/, td.
Calculus. — An Elementary Treatise on the Calculus
for Engineering Students^ with numerous Examples and Problems worked
out. By John Graham, B.A., B.E., Demonstrator and Instructor in
Mathematics in the City and Guilds of London Technical College,
Finsbury. Crown 8vo, cloth, ^s, 6d,
Canals. — Waterways and Water Transport in
Different Countries, With a description of the Panama, Suez, Man-
chester, Nicaraguan, and other Canals. By J. Stephen Jeans, Author
of * England's Supremacy,' * Railway Problems,' &c. Numerous illus-
trations, 8vo, cloth, 14J.
Carpentry. — The Elementary Principles of Car-
pentry, By Thomas Tredgold. Revised from the original edition,
and partly re-written, by John Thomas Hurst. Contained in 517
pages of letterpress, and illustrated with 48 plates and 150 wood engrav-
ings. Sixth edition, reprinted from the third, crown 8vo, cloth, I2J-. 6d.
Section I. On the Equality and Distribution of Forces — Section II. Resistance of
Timber— Section III. Construction of Floors— Section IV. Con!>truction of Roofs — Sec-
tion V. Construction of Domes and Cupolas <— Section VI. Construction of Partitions —
Section VII. Scaffolds, Stagbg, and Gantries— Section VIII. Construction of Centres for
Bridees — Secdon IX. Coffer-dajns, Shoring, and Strutting — Section X. Wooden Bridges
and Yiaduct»— Section XI. Joints, Straps, and other Fastenings^Section XII. Timber.
A 2
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Cast Iron. — The Metallurgy of Cast Iron: A
Complete Exposition of the Processes Involved in its Treatment,
Chemically and Physically, from the Blast Furnace to the Testing
Machine. Illustrated. By THOMAS D. West, M. Am. Soc. M.E
Crown 8vo, cloth, lis. 6</.
Chemistry. — Practical Work in Organic Chemistry.
By F. W. Strkatfeild, F.I.C, etc.. Demonstrator of Chemistry at the
City and Guilds Technical College, Finsbmy. With a^ Prefatory Notice
by Professor R. Meldola, p.R.S., F.LC. Crown 8vo, cloth, y.
Chemists' Pocket Book. — A Pocket-Book for
Chemists^ Chemical Manufacturer s^ Metallurgists^ Dyers^ DisiiUers^
Brewers^ Sugar Refiners^ Photographers ^ Students, etc.^ etc. By Thomas
Bayley, Assoc R.C. Sc Ireland. Fifth edition, 481 pp., royal 32mo,
roan, gilt edges, 5^.
SYNOPSIS OF CONTENTS :
Atomic Weights and Factors — Useful Data— Chemical Calculadoiis— Rules for Indirect
Analysis— Weights and Measures — Thermometers and Barometers — Chemical Phjrsics —
Boiling Points, etc. — Solubility of Substances— Methods of Obtaining Spedfic Gravity— Con-
version of Hydrometers — Strength of Solutions by Specific Gravity— Analysis— Gas Analysis-
Water Analysis— Qualitatixe Analysis and Reactions— Volumetric Anadhrsi»— Manipulation-
Mineralogy — Assayine — Alcohol — Beer — Su^ar — Miscellaneous Technological matter
relating to Potash, Soda, Sulphuric Actd, Chlonne, Tar Products, Petroleum, Milk, Tallow,
Photography, Prices, Wages, Appendix, etc., etc
Coffee Cultivation. — Coffee: its Culture and
Commerce tn all Countries, Edited by C. G. Warnford Lock, F.L.S.
Crown 8vo, cloth, I2J. 6d,
Concrete. — Notes on Concrete and Works in Con-
crete; especially written to assist those engaged upon Public Works. By
John Newman, Assoc. Mem. Inst. C.E. Second edition, revised and
enlarged, crown 8vo, cloth, 6j.
Coppersmithing. — Art of Coppers7nithing : a
Practical Treatise on Working Sheet Copper into all Forms. By John
Fuller, Sen. Numerous engravings^ illustrating almost every branch of
the Art. Royal 8vo, cloth, \2s. 6d.
Corrosion. — Metallic Structures: Corrosion and
Fouling, and their Prevention ; a Practical Aid-Book to the safety of
works in Iron and Steel, and of Ships ; and to the selection of Paints for
them. By John Newman, Assoc. M. Inst. C.E. Crown Svo, cloth, ^s.
Depreciation of Factories. — The Depreciation
of Factories and their Valuation, By EwiNG Matheson, Mem. Inst.
C.E. Second edition, revised, with an Intio.iuction by W. C. Jackson.
Svo, cloth, 7 J. td.
PUBLISHED BY E. & F. N. SPON, LIMtTED.
Drainage. — The Draiftage of Fens and Low Lands
by Gravitation and Steam Power. By W. H. Wheeler, M. Inst C.E.
With plates, 8vo, cloth, lis, 6d,
Drawing, — Hints on Architectural Dratightsmavr
ship. By G. W. TuxFORD Hallatt. Fcap. 8vo, cloth, is, 6d,
Drawing. — The draughtsman s Handbook of Plan
and Map Drawing; including instructions for the preparation of
Engineering, Architectural, and Mechanical Drawings. With numerous
illustrations in the text, and '^'^ plates {imprinted in colours). By G. G.
ANDRi, F.G.S., Assoc. Inst. C.E. 4to, cloth, 91.
Drawing Instruments. — A Descriptive Treatise
on Mathematical Drawing Instruments: their construction, uses, quali-
ties, selection, preservation, and suggestions for improvements, with hints
upon Drawing and Colouring. By W. F. Stanley, M.R.I. Sixth edition,
with numerous illustrations, crown 8vo, cloth, 5/.
Dynamo. — Dynamo- Tenders' Hand-Book. By
F. B. Badt. With 70 illustratiafs. Third edition, l8mo, cloth, 41. td.
Dynamo -Electric Machinery. — Dynamo- Elec-
tric Machinery: a Text-Book for Students of Electro-Technology. By
SiLVANUS P. Thompson, B.A., D.Sc. With 520 illustrations. Fifth
edition, 8vo, cloth, 24r.
Earthwork Slips. — Earthwork Slips and Subsi-
dences upon Public Works: Their Causes, Prevention and Reparation.
Especially written to assist those engaged in the Construction or
Maintenance of Railways, Docks, Canals, Waterworks, River Banks,
Reclamation Embankments, Drainage Works, &c, &c. By John
Newman, Assoc. Mem. Inst. C.E., Author of * Notes on Concrete,' &c.
Crown 8vo, cloth, ^s, 6d,
Electric Lighting. — Electric Lightifig: a Practical
Exposition of the Art, for the use of Engineers, Students, and others
interested in the Installation and Operation of Electrical Plant. Vol. I.
The Generating Plant. By Francis B. Crocker, E.M., Ph.D., Pro-
fessor of Electrical Engineering in Columbia University, New York.
With 152 illustrations, 8vo. cloth, 12s, 6d,
Electric Bells. — Electric Bell Construction : a
treatise on the construction of Electric Bells, Indicators, and similar
apparatus. By F. C. Allsop, Author of * Practical Electric Bell Fitting.'
frith 177 illustrations drawn to scale, crown 8vo, cloth, y, 6d,
CATALOGUE OF SCIENTIFIC BOOKS
Electric Bells. — A Practical Treatise on the
fitting up and maintenance of Electric Bells and all the necessary apparatus.
By F. C. Allsop, Author of * Telephones, their Construction and Fitting.*
Sixth edition, revised. With i8o illustrations^ crown 8vo, cloth, y, 6d.
Electric Currents. — Polyphase Electric Currents
and Alternate Current Motors, By SiLVANUS P. THOMPSON, B.A.,
D.Sc, M.Inst. E.E., F.K.S. With \1\ Uluitrations,^ demy 8vo, cloth,
12/. 6k
Electric Telegraph. — Telegraphic Connections,
embracing recent methods in Quadruplex Telegraphy. By Charles
Thom and Willis H. Jones. With illustrations. Oblong 8vo, cloth,
Electric Testing. — A Guide for the Electric Test-
ing of Telegraph Cables, By CoL V. HosKiCER, Royal Danish Engineers.
Third edition, crown Svo, cloth, 4^. 6^.
Electric Toys. — Electric Toys. Electric Toy-
Making, Dynamo Building and Electric Motor Construction for
Amateurs. By T. O'CoNOR Sloane, Ph.D. With cuts, crown Svo,
cloth, 4 J. 6d.
Electrical Notes. — Practical Electrical Notes and
Definitions for the use oj Engineering Students and Practical Men, By
W. Perren Maycock, Assoc. M. Inst. E.E., Instructor in Electrical
Engineering at the Pitlake Institute, Croydon, together with the Rules
and Regulations to be observed in Electrical Installation Work. Second
edition. Royal 32mo, cloth, red edges, 2j.
Electrical Tables. — Electrical Tables a^id Mevw-
randa. By Silvanus P. Thompson, D.Sc, B.A., F.R.S., and Eustace
Thomas. In waistcoat-pocket size (2 J in. by ij in.), French morocco,
gilt edges, with numerous illustrations^ is.
Electricity. — The Arithmetic of Electricity;
Manual of Electrical Calculations by Arithmetical Methods. By
T. O'Conor Sloane, Ph.D. Crown Svo, cloth, 4J. dd.
Electrical Testing. — A Practical Guide to the
Testing of Insulated Wires and Cables. By HERBERT LAWS Webb,
Member of the American Institute of Electrical Engineers, and of the
Institution of Electrical Engineers, London. Crown Bvo, cloth, 4^. 6d.
PUBLISHED BY E. & F. N. SPON, LIMITED.
Electrical Testing. — A Handbook of Electrical
Testing, By H. R. Kempe, M.I.E.E. Fourth edition, revised and
enlarged, 8vo, cloth, i&r.
Electricity. — Electricity, its Theory, Sources, and
Applications, By John T. Sprague, M.Inst. E.E. Third edition,
thoroughly revised and extended, with numerous illustrations and tables,
crown §vo, cloth, 15^.
Electricity in the House. — Domestic Electricity
for Amateurs, Translated from the French of £. Hospitalier, Editor
of *L*Electricien,' by C. J. Wharton, M. Inst. E.E. Numerous
illustrations. Demy 8vo, cloth, dr.
CONTENTS :
X. Production of the Electric Current— 9. Electric Bells— 3. Automatic Alarms— 4. Domestic
Telephones — 5. Electric Docks— 6. Electric Ligners — 7. Domestic Electric Lighting—
6. Domestic Application of the Electric Light— 9. Electric Motors— zo. Electrical Locomo-
tion — zz. Electrotyping, Plating, and Gilding — la. Electric Recreations^za. Various appli-
cations — ^Workshop of the Electrician.
Electricity on Railways.— Z;^^ Application of
Electricity to Railway Working, By W. E. Langdon, M. Inst. E.E.,
Superintendent Electrical Department, Midland Railway. With 142
illustrations, 8vo, cloth, loj. 6^.
Electro-Magnet.- The Electro-Magnet and Electro-
magnetic Mechanism, By SiLVANUS P. THOMPSON, D.Sc., F.R.S.
With 213 illustrations. Second edition, Svo, cloth, 151.
Electro-Motors. — Notes on design of Small Dy
name. By Geo. Halliday, Whitworth Scholar, Professor of Engineer-
ing at the Hartley Institute, Southampton. Plates^ 8vo, cloth, 2s, 6d,
Electro-Motors. — The practical management of
Dynamos and Motors, By Francis B. Crocker, Professor of Electrical
Engineering, Columbia College, New York, and Schuyler S. Wheeler,
D.Sc. CutSy crown 8vo, cloth, 4r. 6</.
Engineering Drawing. — Practical Geometry,
Perspective and Engineering Drawing ; a Course of Descriptive Geometry
adapted to the Requirements of the Engineering Draughtsman, including
the determination of cast shadows and Isometric Projection, each chapter
being followed by numerous examples ; to which are added rules for
Shading, Shade-lining, etc, together with practical instructions as to the
Lining, Colouring, Printing, and general treatment of Engineering Draw-
ings, with a chapter on drawing Instruments. By George S. Clarke,
Capt R.E. Second edition, with 21 plates* 2 vols., cloth, lOf. 6d.
8 CATALOGUE OF SCIENTIFIC BOOKS
Engineers' Tables. — A Pocket-Book of Useful
Formula and Memorattda for Civil and Mechanical Engineers, By Sir
Guilford L. Molesworth, Mem. Inst C.E., and R. B. Molesworth.
With numerous ii lustrations ^ 782 pp. Twenty-third edition, 32mo»
roan, 6j. synopsis of contents :
Surveying, Levelling, etc.— Strength and Weight of Materials^— Earthwork, Bridcwork*
Masonry, Arches, etc. — Struts, Columns, Beams, and Trusses— Flooring, Roofing, and Root
Trusses— Girders, Bridges, etc. — Railways and Roads — Hydraulic Formulae— Canals. Sewers,
Waterworks, Docks — liTigation and Breakwaters— Gas, Ventilation, and Warming^Heat,
Light, Coloiur, and Sound — Gravity : Centres, Forces, and Powers — Millwork, Teeth of
Wheels, Shadftine, etc.— Workshop Recipes— Sundry Machinery — Animal Power— ^team and
the Steam Engine— Water-power, Water-wheels, Turbines, etc. — Wind and Windmills-
Steam Navigation, Ship Building, Tonnaf^e, etc. — Gunnery, Projectiles, etc.— Weights,
Measures, and Moneys— Trigonometry, Conic Sections, and Curves — Tel^;raphy — Mensura-
tion—Tables of Areas and Circumference, and Arcs of Circles — Logarithms, Square and
Cube Roots, Powers— Reciprocals, etc. — Useful Numbers— Differential and Int^;ral Calcu-
lus—Algebraic Signs— Telqpaphic Construction and Formulae.
Engineers' Tables, — Spons Tables and Memo-
randafor Engineers, By J. T. HuRST, C.E. Twelfth edition, revised and
considerably enlarged, in waistcoat-pocket size (2 j in. by 2 in.), roan,
gilt edges, is,
Experimental Science. — Experimental Science:
Elementary, Practical, and Experimental Physics. By Geo. M. Hopkins.
Illustrated by S90 engravings, 840 pp., 8vo, cloth, I dr.
Factories. — Our Factories, WorksJiops, and Ware-
houses: their Sanitary and Fire-Resisting Arrangements. By B. H.
Thwaite, Assoc Mem. Inst C.E. With 183 wood engravings, crown
8vo, cloth, 9x.
Fermentation. — Practical Studies in Fermentation,
being contributions to the Life History of Micro-Organisms. By Emfl
Ch. Hansen, Ph.D. Translated by Alex. K. Miller, Th.D.,
Manchester, and revised by the Author. With numerous illustrations y
8vo, cloth, 1 2 J. (id.
Foundations. — Notes on Cylinder Bridge Piers
and the Well System of Foundations, By JOHN Newman, Assoc. M.
Inst. C.E., 8vo, cloth, 6x.
Founding. — A Practical Treatise on Casting and
Founding, including descriptions of the modem machinery employed in
the art. By N. E. Spretson, Engineer. Fifth edition, with 82 plates
drawn to scale, 412 pp., demy 8vo, cloth, i8x.
French Polishing. — The French - Polishers
Manual, By a French-Polisher; containing Timber Staining, Washing,
Matching, Improving, Painting, Imitations, Directions for Staining,
Sizing, Embodying, Smoothing, Spirit Varnishing, French-Polishing,
Directions for Repolishing. Third edition, royal 32mo, sewed, td.
PUBLISHED BY E. & F. N. SPON, LIMITED.
Furnaces. — Practical Hints on the Working and
Construction oj Regenerator Funtaces, being an Explanatory Treatise on
the System of Gaseous Firing applicable to Retort Settings in Gas Works.
By Maurice Graham, Assoc. Mem. Inst. C.E. Cuts^ 8vo, cloth, y.
Gas Analysis. — T/ie Gas Engineers' Laboratory
Handbook. By JOHN HORNBY, F.I.C., Honours Medallist in Gas
Manipulation, City and Guilds of London Institute. Numerous illus'
trationsy crown 8vo, cloth, 6x.
contents:
The Balance — ^Weights and Weighing — Sampling— Mechanical Division — Drying and
Desiccation — Solution and Evaporation — Precipitation — Filtration and Treatment ot
Precipitates — Simple Gravimetric Estimations — ^Volumetric Analyses^Special Analyses
required by Gas Works— Technical Gas Analysis— Gas Referees' Instructions, etc. etc
Gas and Oil Engines. — Gas, Gasoline and Oil
Vapour Engines : a New Book Descriptive of their Theory and Power,
illustrating their Design, Construction and Operation for Stationary,
Marine and Vehicle Motive Power. Designed for the general informa-
tion of every one interested in this new and popular Prime Mover. By
G. D. Hiscox, M.E. Numerous engravings ^ 8vo, cloth, 12^. dd.
Gas Engines. — A Practical Handbook on the
Care and Management of Gas Engines, By G. Lieckfeld, C.E.
Authorised Translation by G. Richmond, M.E. With instructions for
running Oil Engines. i6nio, cloth, 31. 6^.
Gas Engineering. — Manual for Gas Engineering
Students. By D. Lee. i8mo, cloth, is.
Gas Works. — Gas Works: their Arrangement,
Construction, Plant, and Machinery. By F. Colyer, M. Inst. C.E.
With Zl folding plates, 8vo, doth, I2s. 6d.
Gold Mining. — Practical Gold-Mining : a Com-
prehensive Treatise on the Origin and Occurrence of Gold-bearing Gravels,
Rocks and Ores, and the Methods by which the Gold is extracted. By
C. G. Warnford Lock, co- Author of • Gold : its Occurrence and Extrac-
tion.' With. 8 plates and 275 engravings in the text^ 788 pp., royal 8vo,
cloth, 2/. 2J-.
Graphic Statics. — The Elements of Graphic Statics.
By Professor Karl Von Ott, translated from the German bv G. S
Clarke, Capt R.E., Instructor in Mechanical Drawing, Royal Indian
Engineering College. With 93 illustrations, crown 8vo, doth, 51.
Graphic Statics. — The Principles of Graphic
Statics. By George Sydenham Clarke, Capt. Royal Engineers.
With 112 illustratiofu. Third edition, 4to, cloth, lis. 6d,
lo CATALOGUE OF SCIENTIFIC BOOKS
Graphic Statics. — A New Method of Graphic
Statics, applied ic the construction of Wrougbt-Iron Girders, practically
illustrated by a series of Working Drawing of modem t)rpe. By
Edmund Olander, of the Great Western Railway, Assoc. Mem. InsL
C.E. Small folio, cloth, lar. 6d.
Heat Engine. — Theory and Construction of a
BationalHeat Motor, Translated from the German of Rudolf Diesel by
Bryan Donkin, Mem. Inst. C.E. Numerous cuts and plates, 8vo, cloth, 6x.
Hot Water. — Hot Water Supply: a Practical
Treatise upon tlie Fitting of Circulating Apparatus in connection with
Kitchen Range and other Boilers, to supply Hot Water for Domestic and
General Purposes. With a Chapter upon Estimating. By F. Dye.
With illustrations, crown 8vo, cloth, y.
Hot Water. — Hot Water Apparatus: an Ele-
mentary Guide for the Fitting and Fixing of Boilers and Apparatus for
the Circulation of Hot Water for Heating and for Domestic Supply, and
containing a Chapter upon Boilers and Fittings for Steam Cooking. By
F. Dye. 32 illustrations, fcap. 8vo, cloth, is. 6d,
Household Manual. — Spons Household Manual :
a Treasury of Domestic Receipts and Guide for Home Management
Demy 8vo, cloth, containing 975 pages and 250 illustrations, price *js, bd.
principal contents :
Hints for selecting a good House — Sanitation — Water Supply — Ventilation and Wanning
— Lighting — Furniture and Decoration — ^Thieves and Fire— The Larder — Curing Foods for
lengthened Prcser\ation — The Dairy — The Cellar — The Pantry — ^The Kitchen — Receipts for
Disnes — The Housewife's Room— Housekeeping, Marketing — The Dining-Room — The
Drawing-Room — The Bedroom — The Nursery — The Sick-Room — The Bath-Room — The
Laundry — The School-Room — The Playground — The Work-Room — The Library— The
Garden — ^The Farmyard — Small Motors — ^Household Law.
House Hunting. — Practical Hints on Taking a
House, By H. Percy Boulnois, Mem. Inst. C.E., City Engineer,
Liverpool, Author of * The Municipal and Sanitary Engineer*s Hand-
book,* * Dirty Dustbins and Sloppy Streets,* &c. iSmo, doth, is, 6d,
Hydraulics. — Simple Hydraulic Formulce. By
T. W. Stone, C.E., late Resident District Engineer, Victoria Water
Supply. Crown 8vo, cloth, 4r.
Hydraulic yidichmtvy .— Hydraulic Steam and
Hand-Power Lifting and Pressing Machinery, By Frederick Colyer,
M. Inst. C.E., M. Inst M.E. Second edition, revised and enlarged. With
88 plates, 8vo, cloth, 28/.
Hydraulic Machinery. — Hydraulic Machinery.
With an Introduction to Hydraulics. By Robert Gordon Blaine,
Assoc. M. Inst. C.E., &c. With 272 illustrations, 383 pp. 8vo, cloth, 14^.
PUBLISHED BY E. & F. N. SPON, LIMITED. ii
Hydraulic Motors. — Water or Hydraulic Motors.
By Philip R. Bjorling. With 206 illustraHons^ crown 8vo, doth, 9/.
CONTENTS :
1. Introduction — ■. Hydraulics relating to Water Motors— 3. Water-wheels— 4. Brexist
Water-wheels— s. Overshot and High-breast Water-wheels — 6. Pelton Water-wheels — 7.
Genezal Remarks on Water-wheels — 8. Turbines— o. Outward-flow Turbines — xo. Inward-
flow Turbines — xx. Mixed-flow Turbines — xa. Parallel-flow Turbines— 13.. Circuznferential-
flow Turbines — 14. Regulation of Turbmes — X5. Details of Turbines — 16. Water-pressure or
Hydraulic Engines— xy. Reciprocating Water-pressure Engines— x8. Rotative Water-
pressure Engines — zo. Oscillating Water-pressure Engines — ao. Rotary Water-pressure
Engines— ax. General Remarks and Rules for Water-pressure Engines — aa. Hydrauhc Rams
—33. Hydraulic Rams without Air Vessel in Direct Communication with the Drive Pipe —
a4. Hydraulic Rams with Air Vessel in Direct Communication with the Drive P^pe — 35.
Hydraulic Pumping Rams — a6. Hydraulic Ram Engines — aj. Details of Hydraulic Rams—
a8. Rules, Formulas, and Tables for Hydraulic Rams — 39. Measuring Water in a Stream
and over a Weir— Index.
Hydropathic Establishments. — The Hydro-
pathic Establishment and its Baths, By R. O. Allsop, Architect.
Author of * The Turkish Bath.' Illustrated with plates and sections, 8vo,
cloth, 5j. contents :
General Considerations — Requirements of the Hydropathic Establishment — Some existing
Institutions — Baths and Treatments and the arrangement of the Bath-House — Vapour Baths
and the Russian Bath — ^The Douche Room and its appliances — Massage and Electrical
Treatment— Pulverisation and the Mont Dore Cure — Innalation and the Pine Cure — The
Sun Bath.
Ice Making. — Theoretical and Practical Ammonia
RefrigercUion^ a work of Reference for Engineers and others employed in
the management of Ice and Refrigeration Machinery. By Iltyd L.
Redwood, Assoc. Mem. Am. Soc. of M.E., Mem. Soc. Chemical Indus-
try. With 2^ pages of tables. Square l6mo, cloth, 41. 6</.
Indicator. — Twenty Years with the Indicator. By
Thomas Pray, Jun., C.E., M.E., Member of the American Society of
Civil Engineer!. With illustrations^ royal 8vo, cloth, lOf. 6^.
Indicator. — A Treatise on the Richards Steam-
Engine Indicator and the Development and Application of Force in the
Steam- Engine. By Charles T. Porter. With illustrations. Fourth
edition, revised and enlarged, 8vo, cloth, 9^.
Induction Coils. — Induction Coils and Coil
Making : a Treatise on the Construction and Working of Shock, Medical
and Spark Coils. By F. C. Allsop. Second edition, with 125 illustra-
tions^ crown 8vo, cloUi, 3j. 6d.
Iron. — The Mechanical and other Properties of Iron
and Steel in connection with their Chemical Composition. By A, VOSMAER,
Engineer. Crown 8vo, cloth, 6^-.
CONTENTS :
The metallurgical behaviour of Carbon with Iron and Steel, also Manganese — Silicon —
Phosphorus — Sulphur — Copper — Chromium — Titanium— Tungsten — ^Aluminium— Nickel-
Cobalt — ^Arsenic — ^Analyses of Iron and Steel, &c.
12 CATALOGUE OF SCIENTIFIC BOOKS
Iron Manufacture . — Roll- Turning /or Sections in
SUd and Iroriy working drawings for Rails, Sleepers, Girders, Bulbs,
Ties, Angles, &c, also Blooming and Cogging for Plates and Billets.
By Adam Spencer. Second edition, with 78 large plates. Illustrations
of nearly every class of work in this Industry.- 4to, cloth, i/. lar.
Locomotive. — The Construction of the Modem
Locomotive, By Gkorge Hughes, Assistant in the Chief Mechanical
Engineer's Department, Lancashire and Yorkshire Railway. Numerous
engravings^ 8vo, cloth, 9J.
CONTENTS :
The Boiler— The Foundry — the Use of Steel Castings— Brass Foundry — The For^e —
Smithy, indudiag Springs— Coppersmiths' Work — The Machine Shop — Erecting.
Lime and Cement. — A Manual of Lime and
Cement^ their treatment and use in construction. By A. H. Heath.
Crown 8vo, cloth, ts.
Liquid Fuel. — Liquid Fuel for Mechanical and
Industrial Purposes. Compiled by E. A. Brayley Hodgetts. WiUk
wood engravings, 8vo, cloth, $s.
Machinery Repairs. — The Repair and Mainten-
ance of Machinery ; a Handbook of Practical Notes and Memoranda for
Engineers and Machinery Users. By T. W. Barber, C.E., M.E.,
Author of * The Engineers' Sketch Book.' With about 400 illustrations^
8vo, cloth, lox. (yd.
Mechanical Engineering. — Handbook for Me-
chanical Engineers. By Henry Adams, Professor of Engineering at
the City of London College, Mem. Inst. C.E., Mem. InSt M.E., &c.
Fourth edition, revised and enlarged. Crown 8vo, cloth, Ts, 6d,
CONTENTS :
Fundamental Principles or Mechanics — Varieties and Properties of Materials — Strength
of Materials and Structures — Pattern Making — Moulding and Founding — Forging, Welding
and Riveting — Workshop Tools and General Machinery — 1 ransmission of Power, Friction
and Lubrication — Thermodynamics and Steam — Steam Boilers — ^The Steam Engine— Hy-
draulic Machinery—Electrical Engineering — Sundry Notes and Tables.
Mechanical Engineering. — The Mechanician :
a Treatise on the Construction and Manipulation of Tools, for the use and
instruction of Young Engineers and Scientific Amateurs, comprising the
Arts of Blacksmithing and Forging ; the Construction and Manufacture
of Hand Tools, and the various Methods of Using and Grinding them ;
description of Hand and Machine Processes ; Turning and Screw Cutting.
By Cameron Knight, Engineer. Containing 1147 illustrations ^ and
397 pages of letter-press. Fourth edition, 4to, cloth, i8j.
PUBLISHED BY E. & F. N. SPON, LIMITED. 13
Mechanical Movements. — The Engineers^ Sketch-
Book of Mechanical Movements t Devices ^ Apfliances^ Contrivances^ Details
employed in the Design and Construction 0/ Machinery for every purpose.
Collected from numerous Sources and from Actual Work. Classined and
Arranged for Reference. IVith 2600 Illustrations, By T. W. Barber,
Engineer. Third edition, 8vo, cloth, lox. 6d.
Metal Plate ^ot^.— Metal Plate Work: its
Patterns and their Geometry, Also Notes on Metals and Rules in Men-
suration for the use of Tin, Iron, and Zinc Plate-workers, Coppersmiths,
Boiler-makers and Plumbers. By C. T. Millis, M.I.M*£« Second
edition, considerably enlarged. fVith numerous illustrations. Crown
8vo, cloth, 9^.
Metrical TbXA^s.— Metrical Tables. By Sir G. L.
Molesworth, M.I.C.E. 32mo, doth, is, 6d,
Mill-Gearing. — A Practical Treatise on Mill- Gear-
ing^ Wheelsy Shafts^ Riggers^ etc, ; for the use of Engineers. By Thomas
Box. Third edition, with it plates. Crown Svo, doth, Js. 6d.
Mill - Gearing. — The Practical Millwright and
Engineer's Beady Reehoner; or Tables for finding the diameter and power *
of cog-wheels, diameter, weight, and power of shafts, diameter and
strength of bolts, etc By Thomas Dixon. Fourth edition, lamo,
cloth, y.
Mineral Oils. — A Practical Treatise on Mineral
Oils and their By^ Products^ including a Short History of the Scotch Shale
Oil Industry, the Geological and Geographical Distribution of Scotch
Shales, Recovery of Acid and Soda used in Oil Refining, and a list of
Patents relating to Mineral Oils. By Iltyd I. Redwood, Mem. Soc.
Chemical Industry. 8vo, cloth, 15^.
Miners' Pocket-Book. — Miners Pocket-Book : a
Reference Book for Miners, Mine Surveyors, Geologists, Mineralogists,
Millmen, Assayers, Metallurgists, and Metal Merchants all over the
world. By C. G. Warn ford Lock, author of* Practical Gold Mining,'
* Mining and Ore- Dressing Machinery,' &c Second edition, fcap. 8vo,
roan, gilt edges, I2j. dd,
CONTENTS :
Geological Maps — Mineral Veias — Minine Methods — Coal Seanu~-Minerals--Preciou5
Stones — Metals and Metallic Ores~Metaluferous Minerals— Assayins^-Olossarv—LUt »«
Useful Books-Index, &c, &c., &c. * «wary--i^t ol.
14 CATALOGUE OF SCIENTIFIC BOOKS
Mining and Ore-Dressing Machinery. — By
C. G. Warnford Lock, Author of * Practical Gold Mining.* Numtrom
illustrations^ super-royal 4to, cloth, 251.
Mining. — Economic Mining; a Practical Hand-
book for the Miner, the Metallurgist, and the Merchant By C. G.
Warnford Lock, Mem. Inst, of Mining and Metallurgy, Author of
'Practical Gold Mining.' With illustrations^ 8vo, cloth, 2IJ.
Municipal Engineering. — The Municipal and
Sanitary Engineer's Handbook. By H. PERCY BOULNOIS, Mem. Inst.
C.E., Borough Engineer, Portsmouth. With numerous illustrations.
Second edition, demy 8vo, cloth, 151.
CONTENTS :
The Appointment and Duties of the Town Surveyor — TraflB^— Macadamised Roadways-*
Steam Rolling— Road Metal and Breaking — Pitched Pavements — Asphalte— Wood PltTementa
— Footpaths — Kerbs and Gutters — Street Naming and Numbering— Street Lighting — Sewer-
age—Ventilation of Sewers— Disposal of Sewage — House Drainage— Disinfectioa— Gas and
Water Companies, etc.. Breaking up Streets — Improvement of Private Streets — Borrowing
Powers — Artizans' and Labourers^ Dwellings— Public Conveniences— Scavenging, including
Street Cleansing— Watering and the Removing of Snow— Plantini^ Street Trees— Deposit of
Plans— Dangerous Buildings— Hoardings— Obstructions— Improvmf Street Lines — Cellar
Openings — Public Pleasure Ground»— Cemeteries— Mortuaries — Cattle and Ordinary Markets
—Public Slaughter-houses, etc— Giving numerous Forms of Notices, Specifications,, and
General Information upon these and other subjects of great importance to Municipal Engi-
neers and others engaged in Sanitary Work.
Paints. — Pigments^ Paint and Painting. A
Practical Book for Practical Men. By George Terry. With illus-
trations, crown 8vo, cloth, 7^. dd.
Paper Manufacture. — A Text-Book of Paper-
Making. By C. F. Cross and E. J. Bevan. With engravings ^ crown
Svo, cloth, I2s, 6d.
Perfumery. — Perfiwtes and their Preparation^
containing complete directions for making Handkerchief Perfumes,
Smelling Salts, Sachets, Fumigating Pastils, Preparations for the care of
the Skin, the Mouth, the Hair, and other Toilet articles, with a detailed
description of aromatic substances, their nature, tests of purity, and
wholesale manufacture. By G. W. Askinson, Dr. Chem. With 32
engravings^ Svo, cloth, 12^. dd.
Perspective. — Perspective^ Explained and Illus^
trated. By G. S. Clarke, Capt. R.E. With illustrations, Svo, cloth,
3j. 6d,
Phonograph. — The Phonography and How to Con-
struct it. With a Chapter on Sound. By W, Gillett. With engravings
and full working drawingSy crown Svo, cloth, $/.
PUBLISHED BY K & F. N. SPON, LIMITED. 15
Popular Engineering. — Popular Engineering,
being interesting and instructive examples in Civile Alechanical^ Electrical^
Chemical^ Minings Military and Naval Engineering, graphically and
plainly described, and specially written for those about to enter the
Engineering Profession and the Scientific Amateur, with chapters on
Perpetual Motion and Engineering Schools and Colleges. By F. Dye.
With 700 illustrations^ crown 4to, cloth, yx. 6^.
Plumbing. — Plumbings Drainage, Water Supply
and Hot Water Fitting, By JOHN Smeaton, C.E., M.S.A., R.P.,
Examiner to the Worshipful Plumbers' Company. Numerous engravings,
8vo, cloth, 71. 6^
Pumping Engines. — Practical Handbook on
Direct-acting Pumping Engine and Steam Pump Construction, By
Philip R. Bj<$rling. With 20 plates, crown 8vo, cloth, 5J.
Pumps. — A Practical Handbook on Pump Con-
struction, By Philip R. Bjorling. Plates, crown 8vo, cloth, Sj.
CONTENTS ;
Principle of the action of a Pump— Classification of Pumps — Description of various
classes of Pumps— Remarics on designing Pumps— Materials Pumps should be made of for
diflferent kinds of Liauids — Description of various classes of Pump-valves — Materials Pump-
valves should be made of for different kinds of Liquids — Various Classes of Pumi>-budcets—
On designing Pump-buckets — Various Classes of ^ump-pistons — Cup-leathers — ^Air-vessels —
Rules and Formulas, &c, &c.
Pumps. — Pump Details. With 278 illustrations.
By Philip R. Bjorling, author of a Practical Handbook on Pump
Construction. Crown 8vo, cloth, 71. dd,
contents :
Windbores— Foot-valves and Strainers — Clack-pieces, Budcet-door-pieces, and H'Pieces
Working-barrels and Plunger-cases — Plungers or Rams — Piston and Plunger, Bucket and
Plunger, Buckets and Valves — Pump-rods and Spears, Spear-rod Guides, &c. — Valve-swords,
Spindles, and Draw-hooks — Set-ofis or Oflf-sets — Pipes, Pipe-joints, and Pipe-stay>— Pump-
slmgs— Ouide-rods and Guides, Kites, Yokes, and Connectine-rods— L. Bdbs, T Bobs,
Angle or V Bobo, and Balance-beams, Rock-^arms, and Fend-o£f Beams, Cistern^ and Tanks
— Minor Details.
Pumps. — Pumps and Pumping Machinery. By
F. CoLVSR, Mem. Inst C.E., Mem. Inst M.£. Part I., second edition,
revised and enlarged, with 50 plates, 8vo, cloth, i/. &r.
CONTENTS :
Three-throw Lift and Well Pumps— Tonkin's Patent ** Combh " Steam Pump— Thome-
will and Warham's Steam Pump — Water Valves — Water Meters — Centriftigal Pumping
Machinery — ^Airy and Anderson^ Spiral Pumn^— Blowing Engines — ^Air Compressors-
Horizontal High-pressure Eiuines — Horizontal Compound Engines— Reidler Engine— Ver*
tical Compound Pumping Engines — Compound Beam Pumpmg Ennnes — Shonheyder's
Patent Regulator — Comisn Beam Engines — ^Worthington High-^uty Pumping Engine-
Davy's Patent Differential Pumping Engine — Tonkin's Patent Pumping Engine— Lancashire
Boiler— Babcock and Wilcox Watex^tube BoUers.
1 6 CATALOGUE OF SCIENTIFIC BOOKS
Pumps. — Pumps, Historically, Theoretically, and
Practically Considered, By P. R. BjoRLlNG. With 156 illustrations.
Crown 8vo, cloth, yj. 6</.
Quantities. — A Complete Set of Contract Documents
far a Country Lodge^ comprising Drawings, Specifications, Dimensions
(for quantities), Abstracts, Bill of Quantities, Form of Tender and Con-
tract, with Notes by J. Leaning, printed in facsimile of the original
documents, on single sheets fcap., in linen case, 5/.
Quantity Surveying. — Quantity Surveying. By
J. Leaning. With 68 illustrations. Third edition, revised, demy 8vo,
cloth, 1 5 J.
CONTENTS :
A complete Explanation of the London I Schedule of Prices.
Practice. Form of Schedule of Prices.
General Instructions. Analysis of Schedule of Prices.
Order of Taking Off. I Adjustment of Accounts.
Modes of Measurement of the varioiu Trades. > Form of a Bill of Variations.
Use and Waste.
Ventilation and Warming.
Credits, with various Examples of Treatment.
Remarks on Specifications.
Prices and Valuation of Work, with
Examples and Remarks upon each Trade.
Abbreviations. ^ ! The Law as it affects Quantity Surveyors,
Squaring^ the Dimensions. | with Law Reports.
Abstracting, with Examples in illustration of , Taking Off after the Old Method.
each Trade. Northern Practice.
Billing. I llie General Sutement of the Methods
Examples of Preambles to each Trade. | recommended by the Manchester Society
Form for a Bill of Quantities. j of Architects for taking Quantities.
Do. Bill of Credits. Examples of Collections.
Do. Bill for Alternative Estimate. 1 Examples of '* Taking Off" in each Trade.
Restorations and Repairs, and Form of BilL I Remarks on the Past and Present Methods
Variations before Acceptance of Tender. ^ of Estimating.
Errors in a Builder's Estimate. {
Railway Curves. — Tables for Setting out Curves
for Railways^ Canals^ Roads^ etc,^ varying from a radius of five chains
to three miles. By A. Kennedy and R. W. Hackwood. Illustrated^
32mo, cloth, 2J. td
Roads. — The Maintenance of Macadamised Roads.
By T. CODRINGTON, M.I.C.E., F.G.S., General Superintendent of
County Roads for South Wales. Second edition, 8vo, cloth. Is. 6d,
Scamping Tricks. — Scamping Tricks and Odd
Knowledge occasionally practised upon Public Works^ chronicled from the
confessions of some old Practitioners. By John Newman, Assoc. M.
Inst. C.E., author of * Earthwork Slips and Subsidences upon Public
Works,* * Notes on Concrete,* &c. Crown 8vo, cloth, 2s. 6d,
Screw Cutting. — Turners Handbook on Screw
Cuttingt Coning, etc, etc., with Tables, Examples, Gauges, and
Formulae. By Walter Price. Fcap 8vo, cloth, is.
PUBLISHED BY K & F. N. SPON, LIMITED. 17
Screw Cutting. — Screw Cutting Tables for En-
gineers and Machinists, giving the values of the diflferent trains of Wheels
required to produce Screws of any pitch, calculated by Lord Lindsay.
Oblong, cloth, 2s,
Screw Cutting. — Screw Cutting Tables, for the
use of Mechanical Engineers, showing the proper arrangement of Wheels
for cutting the Threads of Screws of any required pitch, with a Table for
making the Universal Gas-pipe Threads and Taps, fiy W. A. Martin,
Engineer. Second edition, oblong, doth, is.
Sewerage. — Sewerage and Sewage Disposal. By
Henry Robinson, Mem. Inst. C.E., F.G.S., Professor of Civil
Engineering, King's College, London, &c., with large folding plate.
Demy 8vo, cloth, 12s. 6d,
Slide Valve. — A Treatise on a Practical Method
of Designing Slide- Vahe Gears by Simple Geometrical Construction, based
upon the principles enunciated in EucUd's Elements, and comprising the
various forms of Plain Slide- Valve and Expansion Gearing ; together with
Stephenson's, Gooch's, and Allan's Link-Motions, as applied either to>
reversing or to variable expansion combinations. By Edward J. Cow-
ling Welch, Mem. Inst M.£. Crown 8vo, cloth, 6;.
Soap. — A Treatise on the Manufacture of Soap and
Candles, Lubricants and Glycerine. By W. Lant Carpenter, B.A.,
B.Sc. With illustrations, new edition, revised, crown 8vo, I2j. hd.
Stair Building. — Practical Stair Building and'
Handrailing by the Square Section and Falling Line System, By W. H.
Wood. Folding plata, post 4to, cloth, lOr. td.
Steanl Boilers. — Steam Boilers^ their Manage-
ment and Working on land and sea. By JamES Peattie. With
illustrations, crown 8vo, cloth, 5^.
Steam Engine. -^ A Practical Treatise on the
Steam Engine^ containing Plans and Arrangements of Details for Fixed
Steam Engines, with E^ys on the Principles involved in Design and
Construction. By Arthur Rigg, Engineer, Member of the Society of
Engineers and of the Royal Institution of Great Britain. Demy 4to,
copiously illustrated with woodcuts and 103 plates, in one Volume*
Second edition, cloth, 25J.
This work is not, in any sense, an elementary treatise« or history of the steam engine, but
Is intended to describe examples of Fixed Steam Engines without entering into the wide
domain of locomotive or marine practice. To this end illustrations will be given of the most
recent arrangements of Horisontal, Vertical. Beam, Pumfung, Winding, Portable, Semi-
portable, Cortiss, Allen, Compound, and other similar Engines, by the most eminent Firms in
ureat Britain and America. ^ The laws relating to the action and precautions to be observed
in the construction of the varoiu details, such as Cylinders, Pistons, Piston-rods, Connecting-
B
i8 CATALOGUE OF SCIENTIFIC BOOKS
rods. Cross-heads, Motion-blocks, Eccentrics, Simple, Expansion, Balanced, aud Equilibrium
Slide-valves, and Valve^earing will be minutely dealt with. In diis connection will be found
articles upon the Velocity of Reciprocating Parts and the Mode of Applying the Indicator,
Heat and Expansion of Steam Governors, and the like. It is the writer's desire to draw
illustrations from every possible source, and give only those rules that present practice deems
correct.
Steam Engine. — The Steam Engine considered as
a Thermodynamic Machine^ a treatise on the ThermodyDamic efficiency
of Steam Engines, illustrated by Tables, Diagrams, and Examples from
Practice. By Jas. H. Cotterill, M.A., F.R.S., Professor of Applied
Mechanics in the Royal Naval College. Third edition, revised and
enlarged, 8vo, cloth, 15^.
Steam Engine. — Steam Engine Management ; a
Treatise on the Working and Management of Steam Boilers. By F.
CoLYSR, M. Inst C.E., Mem. Inst M.£. New edition, i8mo, cloth.
Steam Engine. — A Treatise on Modem Steam
Engines and BoiUrs^ including Land, Locomotive and Marine Engines
and Boilers, for the use of Students. By Frederick Colysr, M. Inst
C.E., Mem. Inst M.£. With 2fi plates, 4to, cloth, I2j. dd.
Sugar. — Tables for the Quantitative Estimation of
the Sugars^ with Explanatory Notes. By Dr. Ernest Wein ; translated,
with additions, by William Frew, Ph.D. Crown 8vo, cloth, 6x.
Sugar. — A Handbook for Planters and Refiners ;
being a comprehensive Treatise on the Culture of Sugar-yielding Plants,
and on the Manufacture, Refining, and Analysis of Cane, Palm, Maple,
Melon, Beet, Sorghum, Milk, and Starch Sugars ; with copious
Statistics of their Production and Commerce, and a chapter on the
Distillation of Rum. By C. G. Warnford Lock, F.L.S., &c. ;
B. E. R. Newlands, F.C.S., F.I.C., Mem. Council Soc. Chemical
Industry ; and J. A. R. Newlands, F.C.S., F.I.C. Upwards of 200
illustrations and many plates, 8vo, cloth, i/. lOf.
Surveying. — A Practical Treatise on the Science of
Land and Engineering Surveyings Levelling^ Estimating Quantities, etc.^
with a general description of the several Instruments required for Sur-
veying, Levelling, Plotting, etc. By H. S. Merrett. Fourth edition,
revis^ by G. W. Usill, Assoc. Mem. Inst. C.E. 41 plates, with illus-
trations and tables, royal 8vo, cloth, I2j. dd.
Surveying and Levelling. — Surveying and
Levelling Instruments theoreiieally and practically described, for construc-
tion, qualities, selection, preservation, adjustments, and uses, with other
apparatus and appliances used by Civil Engineers and Surveyors. By
W. F. Stanley. Second edition. 350 cuts, crown 8vo, cloth, 7/. 6d,
PUBLISHED BY K & F. N. SPON, LIMITED. 19
Tables of Logarithms! — A B C Five-Figure
Logarithms for general use. By C. J. Woodward, B.Sc Containing
Mantissse of numbers to 10,000. Log. Sines, Tangents, Cotangents, and
Cosines to 10" of Arc. Together with full explanations and simple
exercises showing use of the tables. 41.
Tables of Squares. — Barlow's Tables 0/ Squares,
Cubes, Square Roots^ Cube Roots^ Reciprocals of all Integer Numbers up to
io,ooa Post Svo, cloth, 6x.
Telephones. — Telephones, their Construction and
Fitting, By F. C. Allsop. Fourth edition, revised. With 210 illustra-
tions. Crown Svo, cloth, 5J.
Tobacco Cultivation. — Tobacco Growing, Curing,
and Manufacturing ; a Han(^book for Planters in all parts of the world.
Edited by C. G. Warnford Lock, F.LS. With illustrations. Crown
Svo, doth, *is, dd.
Tropical Agriculture. — Tropical Agriculture: a
Treatise on the Culture, Preparation, Commerce and Consumption of the
principal Products of the Vegetable Kingdom. By P. L. SiMMONDS,
F.LS., F.R.C.I. New edition, revised and enlarged, Svo, cloth, 2IJ.
Turning. — The Practice of Hand Turning in Wood,
Ivory, Shelly etc,, with Instructions for Turning such Work in Metal as
may be required in the Practice of Turning in Wood, Ivory, etc ; also
an Appendix on Ornamental Turning. (A book for beginners.) By
Francis Campin. Third edition, with wood engravings, crown Svo,
cloth, 3x. 6d,
Valve Gears. — Treatise on Valve- Gears, with
special consideration of the Link-Motions of Locomotive Engines. By
Dr. GusTAV Zeuner, Professor of Applied Mechanics at the Confede-
rated PoljTtechnikum of Zurich. Translated from the Fourth German
Edition, by Professor J. F. Klein, Lehigh University, Bethlehem, Pa,
Illustrated, Svo, cloth, 12s, 6d.
Varnish. — The practical Polish and Varnish-Maker ;
a Treatise containing 750 practical Receipts and Formulae for the Manu-
facture of Polishes, Lacquers, Varnishes, and Japans of all kinds, for
workers in Wood and Metal, and directions for using same. By H. C.
Standage (Practical Chemist), author of 'The Artist's Manual of
Pigments.' Crown Svo, cloth, ts,
B 2
20 CATALOGUE OF SCIENTIFIC BOOKS
Ventilation. — Health and Comfort in House Build-'
ing; or, Ventilation with Warm Air by Self-acting Suction Power.
With Review of the Mode of Calculating the Draught in Hot-air Flues,
and with some Actual Experiments by T. Drysdals, M.D., and J. W.
Hayward, M.D. With plates and woodcuts. Third edition, with some
New Sections, and the whole carefully revised, 8vo, cloth, 7^. 6^
Warn\ing and Ventilating. — A Practical
Treatise upon Warming Buildings by Hot Water^ and upon Heat and
Heating Appliances in general ; with an inquiry respecting Ventilation,
the cause and action of Draughts in Chimneys and Flues, and the laws
relating to Combustion. By Charles Hood, F.R.S. Re-written by
Frederick Dye. Third edition. 8vo, cloth, 15/.
Watchwork. — Treatise on Watchwork, Past and
Present, By the Rev. H. L. Nelthropp, M.A., F.S.A. With 32
illustrations^ crown 8vo, cloth, dr. td,
CONTENTS :
Definitions of Words and Terms used in Watchwork— Toob — ^Time— Historical Sum-
mary—On Calculations of the Numbers for Wheels and Pinions; their Proportional Sizes,
Trains, etc.— Of Dial Wheels, or Motion Work— Length of Time of Going wtdiout Winding
up — The Verge — ^The Horizontal— The Duplex— The Lever— The ChroncHnetei^— Repeating
Watches— Keyless Watches— The Pendulum, or Spiral Spring— Compensation— Jewelling of
Pivot Holes— Oerkenwell — Fallacies of the Trade — Incapacity of Workmen— How to Choose
and Use a Watch, etc.
Water Softening. — Water Softening and Purifi-
cation : the Softening and Clarification of Hard and Dirty Waters. By
Harold Collet. Crown 8vo, cloth, ^s.
Waterworks. — T/ie Principles of Waterworks
Engineering, By J. H. Tudsbery Turner, B.Sc, Hunter Medallist
of Glasgow University, M. Inst C.E., and A. W. Brightmore, M.Sc,
Assoc. M. Inst. C.E. With illustrations, medium 8vo, cloth, 251.
Well Sinking. — Well Sinking. The modern prac-
tice of Sinking and Boring Wells, with geological considerations and
examples of Wells. By Ernest Spon, Assoc. Mem. Inst. C.K
Second edition, revised and enlarged. Crown Svu, cloth, los, 6d,
Wiring. — Incandescent Wiring Hand-Book. By
F. B. Badt, late 1st Lieut. Royal Prussian Artillery. With 41 illustra-
tions and 5 tables, i8mo, cloth, 4^. 6d,
Wood-working Factories. — On the Arrange-
ment^ Care, and Operation of Wood-working Factories and Afachinery,
forming a complete Operator's Handbook. By J. Richard, Mechanical
Engineer. Second edition, revised, woodcuts, crown 8vo, cloth, 5^,
PUBLISHED BY K & F. N. SPON, LIMITED. 21
SP0N8' DICTIONARY OF ENGINEERING,
CIVIL, MECHANICAL, MILITAB7, & NATAL,
WITH
Teohnloal Terms in Frenoh, German, Italian, and Spanish.
In 97 numbers, Super-royal Svo, containing 3132 printed pages and 7414
engravings. Any number can be had separate : Nos. i to 95 is, each,
post free ; Nos. 96, 97, 2x., post free.
Abacus
Adhesion ..
Agricultural Engines
Air-Chamber
Air-Pump ..
Algebraic Signs ..
Alloy
Aluminium
Amalgamating Machine
Ambulance
Anchors ..
Anemometer
Angular Motion . .
Angle-iron..
Angle of Friction . .
Animal Charcoal Machine
Antimony, 4 ; Anvil
Aqueduct, 4 ; Arch
Archimedean Screw
Arming Press
Armour, 5 ; Arsenic
Artesian Well
Artillery, 5 and 6 ; Assay
Atomic Weights ..
Auger, 7 ; Axles . .
Baknce, 7 ; Ballast
Bank Note Machinery
Bam Machinery ..
Barker's Mill
Barometer, 8 ; Barracks
Complete List of all the Subjects :
Barrage .. ..
mg
Nos.
X
I
and 2
2
2
2
2
2
2
2
2
2 and 3
3 and 4
.. 3
.. 3
.. 4
.. 4
.. 4
.. 4
4 and 5
.. 5
.. 5
.. 6
6 and 7
.. 7
.. 7
.. 7
7 and 8
.. 8
.. 8
Nos.
.. .. ..8 and 9
Battery 9 and 10
Bell and Bell-hanging .. ..10
Belts and Belting .. ..10 and 1 1
Bismuth .. .. .. ., 11
Blast Furnace
Blowin<; Machine
Body Plan..
Boilers
Bond . . • •
Bone Mill ..
Boot-making Machinery
Boring and Blasting
Brake
Bread Machine
Brewing Apparatus
Brick-making Machines
Bridges
Buffer
Cables
Cam, 29; Canal ..
Candles
Cement, 30 ; Chimney
Coal Cutting and Washing Ma-
chinery .. ., .. .. 31
Coast Defence .. .. 3i» 32
Compasses.. .. .. ..32
Construction .. ..32 and 33
Cooler, 34; Copper .. ••34
Cork-cutting Machine .. ••34
11 and 12
.. 12
12 and 13
13. I4» 15
15 and 16
.. 16
.. 16
16 to 19
19 and 20
.. 20
20 and 21
.. 21
21 to 28
.. 28
28 and 29
••^^^
29 and 30
30
22
CATALOGUE OF SCIENTIFIC BOOKS
••
Corrosion
Cotton Machinery
Damming ..
Details of Engines
Displacement
Distilling Apparatus
Diving and Diving Bells
Docks
Drainage ..
Drawbridge
Dredging Machine
Dynamometer
Electro-Metallurgy
Engines, Varieties
Engines, Agricultural
Engines, Marine ..
Engines, Screw ..
Engines, Stationary
Escapement
Fan > • . .
File-cutting Machine
Fire-arms ..
Flax Machinery ..
Float Water-wheels
Forging
Founding and Casting
Friction, 50 ; Friction, Angle of 3
Fuel, 50; Furnace .. 50, 51
Fuze, 51 ; Gas .. .. .. 51
Gearing .. .. .. 51, 52
Gearing Belt .. .. 10, 1 1
Geodesy .. .. .. 52 and 53
Glass Machinery .. .. •• 53
Gold, 53, 54 ; Governor . . . . 54
Gravity, 54 ; Grindstone .. 54
Gun-carriage, 54; Gun Metal .. 54
Gunnery .. .. .. 54 to 56
Nos.
34 and 35
.. 35
35 to 37
37,38
.. 38
38 and 39
39 and 40
40 and 41
.. 41
.. 41
41 to 43
43» 44
44»45
I and 2
74, 75
89,90
91,92
45, 46
.. 46
.. 46
46,47
47,48
.. 48
.. 48
48 to 50
Gunpowder
Gun Machinery ..
Hand Tools
Hanger, 58 ; Harbour
Haulage, 58, 59 ; Hinging
Hydraulics and Hydraulic Ma
56
56,57
57,58
.. 58
59
chinery
Ice-making Machine
India-rubber
Indicator ..
Injector
Iron
Iron Ship Building
Irrigation ..
59 to 63
.. 63
.. 63
. . 63 and 64
. • 64
.. 64 to 67
.. ,. 67
. . 67 and 68
Nos.
Isomorphism, 68 ; Joints .. 68
Keels and Coal Shipping 68 and 69
Kiln, 69 ; Knitting Madiine .. 69
Kyanising .. •. .. . •• 69
Lamp, Safety .. .. 69, 70
Lead .. .. .. .. jo
Lifts, Hoists .. .. 70, 71
Lights, Buoys, Beacons .. 71 and 72
Limes, Mortars, and Cements .. 72
Locks and Lock Gates .. 72, 73
Locomotive .. ., -.73
Machine Tools .. .. 73, 74
Manganese .. .. ••74
Marine Engine .. •'74 and 75
Materials of Construction 75 and 76
Measuring and Folding . . . . 76
Mechanical Movements .. 76, 77
Mercury, 77; Metallurgy .. 77
Meter .. .. .. 77, 78
Metric System .. .. ..78
Mills .. .. .. 78, 79
Molecule, 79 ; Oblique Arch .. 79
Ores, 79, 80 ; Ovens .. ..80
Over-shot Water-wheel .. 80, 81
Paper Machinery . . .. ..81
Permanent Way .. .. 81, 82
Piles and Pile-driving . . 82 and 83
Pipes .. .. .. 83, 84
Planimeter .. .. ..84
Pumps . . . . . . 84 and 85
Quarrying .. .. .. ..85
Railway Engineering .. 85 and 86
Retaining Walls .. .. ..86
Rivers, 86, 87 ; Riveted Joint .. 87
Roads 87, 88
Roofs .. .. .. 88, 89
Rope-making Machinery .. 89
Scaffolding .. .. ..89
Screw Engines .. .. 89, 90
Signals, 90; Silver .. 90» 91
Stationary Engine .. 91, 92
Stave-making & Cask Machinery 92
Steel, 92 ; Sugar Mill . . 92, 93
Surveying and Surveying Instru-
ments .. .. .. 93, 94
Telegraphy .. .. 94» 95
Testing, 95 ; Turbine .. ••95
Ventilation .. 95, 96, 97
Waterworks ,. .. 96, 97
Wood-working Machinery 96, 97
Zinc .. ,, .. 96, 97
PUBLISHED BY E. & F. N. SPON, LIMITED. 23
In Mipar-royal 8vob iz68 pp^ wiiA S400 HlmtirmUoiu^ in 3 'Divisions, doth, price i^ 6d*
•ach ; or x vol., doth, •L ; or half-morocco, a/. 8f .
A SUPPLEMENT
TO
SPONS' DICTIONARY OF ENGINEERING.
Edited by ERNEST SPON, Mxmb. Soc. Enginkbks.
Abacus, Counters, Speed
Indicators, and Slide
Rule.
Agricoltnral Implements
and Machinery.
Air Compressors.
Animal Charcoal Ma-
chinery.
Antimony.
Axles and Axle-boxes.
Bam Machinery.
Belts and Belting.
Blasting. Boilers.
Brakes.
Brick Machinery.
Bridges.
Cages for Mines.
Calcnlos, Differential and
IntegraL
Canals.
Carpentry.
Cast Iron.
Cement, Concrete,
Limes, and Mortar.
Chimney Shafts.
Coal Cleansing and
Washing.
Coal Mining.
Coal Cutting Machines.
Coke Ovens. Copper.
Docks. Drainage.
Dredging Machinery.
Djmamo • Electric and
Magneto-Electric Ma-
chines.
Dynamometers.
Electrical Engineering,
Telegraphy, Electric
Lighting and its prac-
tical details,Telephones
Engines, Varieties of.
Explosives. Fans.
Founding, Moulding and
tlie practical work of
the Foundry.
Gas, Manufacture of.
Hammers, Steam and
other Power.
Heat Horse Power.
Hydraulics.
Hydro-geology.
Indicators. Iron.
lifts, Hoists, and Eleva-
tors.
Lighthouses, Buoys, and
Beacons.
Machine Tools.
Materials of Const
tion.
Meters.
Ores, Machinery and
Processes employed to
Dress.
Piers.
Pile Driving.
Pneumatic Transmis-
sion.
Pumps.
P)rrometers.
Road Locomotives.
Rock Drills.
Rolling Stock.
Sanitary Engineering.
Shafting.
SteeL
Steam Navvy.
Stone Machinery.
Tramways.
Well Sinking.
24 CATALOGUE OF SCIENTIFIC BOOKS.
In demy 4to, handsomely bound in cloth, illustrated with 220 Jull page plates^
Price 1 5 J.
ARCHITECTURAL EXAMPLES
IN BRIOK, STONE, WOOD, AND IRON,
A COMPLETE WORK ON THE DETAILS AND ARRANOEMEKT
OF BUILDING CONSTRUCTION AND DESIGN.
By WILLIAM FULLERTON, Architect.
Containing aao Plates, with numerous Drawings selected from the Architectone
of Former and Present Times.
7%€ Details and Designs are Drawn to Scale, J", \'\ J", and Full siae
keing chiefly used.
The Plates are arranged in Two Parts. The First Part contains
Details of Work in the four principal Building materials, the following
being a few of the subjects in this Part : — ^Various forms of Doors and
Windows, Wood and Iron Roofs, Half Timber Work, Porches,
Towers, Spires, Belfries, Flying Buttresses, Groining, Carving, Church
Fittings, Constructive and Ornamental Iron Work, Classic and Gothic
Molds and Ornament, Foliation Natural and Conventional, Stained
Glass, Coloured Decoration, a Section to Scale of the Great Pyramid,
Grecian and Roman Work, Continental and English Gothic, Pile
Foimdations, Chimney Shafts according to the regulations of the
London County Council, Board Schools. The Second Part consists
of Drawings of Plans and Elevations of Buildings, arranged under the
following heads : — Workmen's Cottages and Dwellings, Cottage Resi-
dences and Dwelling Houses, Shops, Factories, Warehouses, Schools,
Churches and Chapels, Public Buildings, Hotels and Taverns, and
Buildings of a general character.
All the Plates are accompanied with particulars of the Work, with
Explanatory Notes and Dimensions of the various parts.
Spedmen Paga, rtdutidjivm Iht origimalt.
28
CATALOGUE OF SCIENTIFIC BOOKS
Crown 8yo, doth, 485 pages, with illustrations, St,
WORKSHOP RECEIPTS.
SECOND SERIES.
Synopsis of Contents.
Addimetry and Alkali-
metry.
Albumen.
Alcohol.
Alkaloids.
Baking-powders.
Bitters.
Bleadiing.
Boiler Incrustations.
Cements and Lutes.
Cleansing.
Confectionery.
Copying.
Disinfectants.
Dyeing, Staining, and
Colouring.
Essences.
Extracts.
Fireproofing.
Gelatine, Glue, and Size.
Glycerine.
Gut.
Hydrogen peroxide.
Ink.
Iodine.
Iodoform.
Isinglass.
Ivory substitutes.
Leather.
Luminous bodies.
Magnesia.
Matches.
Paper.
Parchment
Perchloric add.
Potassium oxalate.
Preserving.
Pigments, Paint, and Painting : embracing the preparation of
Pignunts, induding alumina lakes, blacks (animal, bone, Frankfort, ivory,
lamp, sight, soot), blues (antimony, Antwerp, cobalt, caeruleum, Egyptian,
manganate, Paris, Peligot, Prussian, smalt, ultramarine), browns (bistre,
hinau, sepia, sienna, umber, Vandyke), greens (baryta, Brighton, Brunswick,
chrome, cobalt, Douglas, emerald, manganese, mitis, mountain, Prussian,
sap, Scheele's, Schwemfurth, titanium, verdigris, zinc), reds (Brazilwood lake,
carminated lake, carmine, Cassius purple, cobalt pink, cochineal lake, colco-
thar, Indian red, madder lake, red chalk, red lead, vermilion), whites (alum,
baryta, Chinese, lead sulphate, white lead — by American, Dutch, French,
German, Kremnitz, and Pattinson processes, precautions in making, and
composition of commercial samples — whiting, Wilkinson's white, zinc white),
yellows (chrome, eamboge, Naples, orpiment, realgar, yellow lakes) ; Paint
(vehides, testing oils, (uiers, grinding, storing, applying, priming, drying,
filling, coats, brushes, surface, water-colours, removmg smell, discoloration ;
miscellaneous paints — cement paint for carton-pierre, copper paint, gold paint,
iron paint, lime paints, silicated paints, steatite paint, transparent paints,
tungsten paints, window paint, zinc paints) ; Painting (general instructions,
proportions of ingredients, measuring paint work ; carriage painting — priming
paint, best putty, finishing colour, cause of cracking, mixing the paints, oils,
driers, and colours, varnishing, importance of washing vehicles, re-vamishing,
how to dry paint ; woodwork painting).
PUBLISHED BY K & F. N. SPON, LIMITED. 29
Crown 8vo, doth, 480 pages, with 183 illustrations, 5/.
WORKSHOP RECEIPTS.
THIRD SERIES.
Uniform with the First and Second Series*
Synopsis of Coktents.
Alloys.
Iridium.
Rubidium.
Aluminium.
Iron and SteeL
Ruthenium.
Antimony.
Lacquers and Lacquering.
Selenium.
Barium.
Lanthanum.
saver.
Beryllium.
Lead.
Slag.
Bismuth.
Lithium.
Sodium.
Cadmium.
Lubricants.
Strontium.
Csesium.
Magnesium.
Tantalum.
Calcium.
Manganese.
Terbium.
Cerium.
Mercury.
Thallium.
Chromium.
Mica.
Thorium.
Cobalt
Molybdenum.
Tin.
Copper.
Nickel
Titanium.
Didyminm.
Niobium.
Tungsten.
Enamels and Glazes.
Osmium.
Uranium.
Erbium.
Palladium.
Vanadium.
Gallium.
Platinimu
Yttrium.
Glass.
Potassium.
Zinc.
Gold.
Rhodium.
Zirconium.
Indium.
Electrics, — Alarms, Bells, Batteries. Carbons, Coils, Dynamos, Micro-
phones, Measuring, Phonographs, Telephones, &a, 130 pp., 112 iUustrattons.
^ t
30 CATALOGUE OF SCIENTIFIC BOOKS
WORKSHOP RECEIPTS.
FOURTH SERIES,
DEVOTED MAINLY TO HANDICRAFTS & MECHANICAL SUBJECTS.
250 niuitratioiii, with Complete Index, and a General Index to the
Four Seriei, 6i.
Waterproofing — rubber goods, cuprammonium processes, miscellaneoos
preparations.
Packing and Storing articles of delicate odour or colour, of a deliquescent
character, liable to ignition, apt to suffer from insects or damp, or easily
broken.
Embalming and Preserving anatomical specimens.
Leather Polishes.
Cooling Air and Water, producing low temperatures, making ice, cooling
syrups and solutions, and separating salts from liquors by refrigeration.
Pumps and Siphons, embracing every useful contrivance for raising and
supplying water on a moderate scale, and moving corrosive, tenacious,
and other liquids.
Desiccating — air- and water-ovens, and other appliances for drying natural
and artificial products.
Distilling — water, tinctures, extracts, pharmaceutical preparations, essences,
perfumes, and alcoholic liquids.
Emulsifying as required by pharmacists and photographers.
Evaporating — saline and other solutions, and liquids demanding special
precautions.
Filtering — water, and solutions of various kinds.
Percolating and Macerating.
Electrotyping.
Stereotyping by both plaster and paper processes.
Bookbinding in all its details.
Straw Plaiting and the fabrication of baskets, matting, etc
Musical Instruments — the preservation, timing, and repair of pianos,
harmoniums, musical boxes, etc
Clock and Watch Mending — adapted for intelligent amateurs.
Photography — recent development in rapid processes, handy apparatus,
numerous recipes for sensitizing and developing solutions, and applica-
tions to modem illustrative purposes.
PUBLISHED BY E. & F. N. SPON, LIMITED. 31
Crown 8vo, cloth, with 373 illustrations, price Ss»
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♦ FIFTH SERIES.
Containing many new Articles, as well as additions to Articles included in
the previous Series, as follows, viz. : —
Anemometers.
Barometers, How to make.
Boat Building.
Camera Lucida, How to use.
Cements and Lutes.
Cooling.
Copying.
Corrosion and Protection of Metal
^ Surfaces.
Dendrometer, How to use.
Desiccating.
Diamond Cutting and Polishing. Elec-
trics. New Chemical Batteries, Bells,
Commutators, Galvanometers, Cost
of Electric Lighting, Microphones,
Simple Motors, Phonogram and
Graphophone, Registering Appa-
ratus, Regulators, Electric Welding
and Apparatus, Transformers.
Evaporating.
Explosives.
Filtering.
Fireproofing, Buildings, Textile Fa-
brics.
Fire-extinguishing Compounds and
Apparatus.
Glass Manipulating. Drilling, Cut-
ting, Breaking, Etching, Frosting,
Powdering, &c.
Glass Manipulations for Laboratory
Apparatus;
Labels. Lacquers.
Illuminating Agents.
Inks. Writing, Copying, Invisible,
Marking, Stamping.
Magic Lanterns, their management
and preparation of slides.
Metal Work. Casting Ornamental
Metal Work, Copper Welding
Enamels for Iron and other Metals,
Gold Beating, Smiths* Work.
Modelling and Plaster Casting.
Netting.
Packing and Storing. Acids, &c.
Percolation.
Preserving Books.
Preserving Food, Plants, &c.
Pumps and Syphons for various
liquids.
Repairing Books.
Rope Tackle.
Stereotyping.
Taps, Various.
Tobacco Pipe Manufacture.
Tying and Splicing Ropes.
Velocipedes, Repairing.
Walking Sticks.
Waterproofing.
32 CATALOGUE OF SCIENTIFIC BOOKS.
In demy 8vo, cloth, 600 pages and 1420 illustrations, 6s.
FOURTH EDITION.
SPONS'
MECHANICS' OWN BOOK;
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Contents,
Mechanical Drawing — Casting and Founding in Iron, Brass, Bronze,
and other Alloys — Forging and Finishing Iron — Sheetmetal Working
^Soldering, Brazing, and Burning — Carpentry and Joinery, embracing
descriptions of some 400 Woods, over 200 Illustrations of Tools and
their uses, Explanations (with Diagrams) of 116 joints and hinges, and
Details of Construction of Workshop appliances, rough furniture,
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Fittings — Gilding, dead and bright, on various grounds — Polishing
Marble, Metals, and Wood — ^Varnishing — Mechanical movements,
illustrating contrivances for transmitting motion — ^Turning in Wood
and Metals^Masonry, embracing Stonework, Brickwork, Terracotta
and Concrete — Roofing with Thatch, Tiles, Slates, Felt, Zinc, &c. —
Glazing with and without putty, and lead glazing — Plastering and
Whitewashing — Paper-hanging — Gas-fitting — Bell-hanging, ordinary
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LONDON: fRlNTBD BY WILLIAM CLOWES AND SONS. UMITEO, STAMFORD STRBST
AND CHARING CROSS.
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