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THE WINDMILL 



AS A PRIME MOVER. 



Br 



ALFRED R. WOLFF, M.E., 

CONSULTING ENGINEER, MEMBER AMERICAN SOCIETY OF MECHANICAL ENGINEERS, 

ETC. 



SECOND EDITION. 
FIRST THOUSAND. 



NEW YORK: 

JOHN WILEY & SONS, 

43-45 East 19th Street. 

1900. 



LIBRARY 

UNIVERSITY OF CALIFORNIA 
DAVIS 




Copyright, 1885. 
By JOHN \rii*£Y & SONS. 






• •• 
• • • • 




• l ; 




»MSON S^S., C-N rt " 



•^ 



IBeofcatefc to 



MY FRIEND 



DR. I. ADLER. 



****;**** 



PREFACE. 



The aim of the author in preparing this work was, to pre- 
sent, in one treatise, a consideration of the more important 
features of windmill theory and practice, sufficient to enable 
the engineer and the user to decide as to the actual state of 
windmill construction, its history and progress, its probable 
direction of development, and the degree of economy attained 
as compared with that of other prime movers. 

He was led to the preparation of the work because the 
information on this topic was confined to articles in periodicals, 
pamphlets, and transactions, together with brief treatises in 
text-books ; no one having as yet made a careful and complete 
study of this important subject. 

During the past nine years the author has had occasion, in 
the course of his professional work, to pay close attention to 
the theory and practice of windmill construction, and has pub- 
lished, at various times, professional notes setting forth some 
of the results of his investigations. These papers met with so 
kind a reception from the engineering fraternity, that he was 
induced to present them in a more connected form, and to 
investigate the subject still farther; so that this first treatise 
on the Windmill as a Prime Mover is now given to the public. 



VI PREFACE. 

Many technical works have been consulted; and proper 
credit has been given, as far as the author is aware, in every 
case. His special thanks are due to a number of prominent 
American steam-pump manufacturers for furnishing data of 
durability and cost of their pumps. Without such data, it 
would have been difficult to present the comparison in Chap. 
IX. on "The Economy and Capacity of the Windmill," which 
is deemed of some value to users in deciding upon the relative 
economic bearing of the windmill as a prime mover. 

Finally, it is but just for the author to express his thanks 
to Messrs. John Wiley & Sons for the encouragement afforded 
in the publication of a work which of necessity will have a 
limited sale. 

38 Park Row, New York, 
June 1, 1885. 



CONTENTS. 



INTRODUCTION. 

THE USE OF THE WINDMILL. 

fAGB 

Windmills, economical motors » I 

Their great use. and appreciation at the present ........ i 

Number in use in America I 

Number manufactured in United States 2 

Windmills not antiquated motors . 2 

The historical relation of windmills and steam-engines 2 

Windmills the most economical motors for specific uses 3 

Power purposes of windmills as defined by wind 3 

The specific uses of windmills 4 

Windmills for pumping and storing water 4 

Windmills for compressing and storing air 4 

Windmills for driving dynamo-machines 4 



CHAPTER I. 

WIND : ITS VELOCITY AND PRESSURE. 

Definition of wind 5 

Average movement and velocity of wind 6 

Table I., showing average movement of wind in America 7 

Velocity of wind required to drive windmills 8 



Vlll CONTENTS. 

PAGE 

Average velocity of wind when driving windmills . 8 

Relation between pressure and velocity of wind 8 

The effect of temperature on this relation 8 

Analytical investigation of this relation 9 

Loss by friction of particles of air in motion . . io 

Table II., showing relation between velocity and pressure of wind . . 12 
Table III. (Rouse-Smeaton), showing relation between pressure and 

velocity of wind 14 

Weisbach on the relation of velocity and pressure of wind 15 

Rankine on the relation of velocity and pressure of wind 16 

Hawksley on the relation of velocity and pressure of wind 17 

Field on the relation of velocity and pressure of wind 18 

Gaudard on the relation of velocity and pressure of wind 18 

Pole on the relation of velocity and pressure of wind 19 

Hagen on the relation of velocity and pressure of wind ...... 20 

Adoption of formula for relation of velocity and pressure of wind . . 21 

Velocity of wind as affected by height of observation 21 

Stevenson's formula for this relation 21 

Archibald's formula for this relation 22 

High wind pressures 22 

Scott on high wind pressures 22 

Bender on high wind pressures across the Atlantic 22 

Gaudard on high wind pressures in England and France . . . . 3 23 

Trautwine on high wind pressures in America 23 

C. Shaler Smith on high wind pressures in America 24 

Hartnup on high wind pressures in Great Britain (Table IV.) .... 25 

Baker on high wind pressures 25 



CHAPTER II. 

THE IMPULSE OF WIND ON WINDMILL BLADES. 

Theoretical analysis ^ 

Theoretical mechanical effect of windmill sail 3° 

Application of Rankine's analysis 3° 

Errors in Weisbach's analysis 3 1 



CONTENTS. ix 



PAGE 



Adoption of formula for theoretical mechanical effect of windmill 

sail 33 

Best angles of impulse 33 

Formula for obtaining best angles of impulse 34 

Formula for obtaining best angles of weather 34 

Table V., showing best angles of weather 35 

Diagram showing best angles of weather and impulse 36 

Best angles for ventilators, etc 37 

Theoretical mechanical effect of windmill of shape of sail for maxi- 
mum effect 37 

Theoretical mechanical effect of windmill with plane sails 40 

Loss of effect by friction of the shaft 41 

Actual mechanical effect of windmill with sails of best angles of 

weather 41 

Actual mechanical effect of windmill with plane sails 42 

Comparison of formulae with results of Coulomb's experiments ... 42 



CHAPTER III. 

THE EARLY HISTORY OF WINDMILLS. 

Beckmann on the early history of windmills 45 

Windmills not used by the Romans 46 

Windmills not invented in the East 46 

Windmills probably first used in Germany 47 

Their use in France in 1 105 47 

Their use in Northamptonshire in 1 143 47 

Their use by the Venetians in 1332 48 

Their use in the Netherlands in 1393 48 

Their use in Frankfort in 1442 48 

German mills older than the Dutch 48 

Mills of Dutch type invented in sixteenth century 49 

Windmills in Holland in fifteenth century 49 

Claims of clergy and landlords in the fourteenth century as to pro- 
prietorship of wind 50 



X CONTENTS. 

CHAPTER IV. 

EUROPEAN WINDMILLS. 

PAGE 

Classification : horizontal and vertical mills 52 

Description of horizontal mills c 2 

Disadvantages of horizontal mills 54 

General description of vertical mills 55 

Illustration of windmill sails ry 

Illustration of post or German mills 59 

General description of post or German mills . 60 

Details of post or German mills 61 

General description of Dutch or tower mills 63 

Detail of Cubitus method of turning dome into the direction of the 

wind 64 

Development of governors for adapting surface of wind wheel to force 

of wind 67 

Meikle's governor for reefing the sails 69 

Cubitt's governor for reefing the sails 70 

Comparison of European and American windmills 73 



CHAPTER V. 

AMERICAN WINDMILLS. — SIDE-VANE GOVERNOR MILLS. 

Comparison of American and European windmills 74 

Superiority of American above European windmills 75 

Classification of types of American windmills 75 

General description of centrifugal-governor type 76 

General description of side-vane governor type 76 

General description of other types 76 

Comparison of centrifugal and side-vane governor types 77 

The Corcoran Windmill 78 

Details of Corcoran Mill for railway water supply 80 

Details of Corcoran Geared Mill 82 



CONTENTS. XI 

' PAGE 

Details of plain tower for Corcoran Mill 83 

The Eclipse Windmill 87 



CHAPTER VI. 

AMERICAN WINDMILLS (CONTINUED). 

Centrifugal-governor Mills. 

General description of Halladay Windmill • 89 

Detail of iron- work of Halladay Windmill 92 

Detail of fan of Halladay Windmill 93 

Economy of Halladay Mill for railroad water supply 94 

Detail of Halladay Geared Mill 95 

The Halladay Mill in Germany ; applications of Friedrich Filler . • 97 

The Aithouse Windmill 97 

The Aithouse Pumping-Mill 99 

The Aithouse Geared Mill 100 

The Adams Windmill 101 

Details of the Aithouse Mill • 102 



CHAPTER VII. 

AMERICAN WINDMILLS (CONCLUDED). 

Other types. — Velocity Regulation^ etc. 

The Buchanan Windmill 104 

The Woodmanse Windmill 106 

The Stover Windmill 106 

The Champion Windmill 109 

The Regulator Windmill 11 1 

The Strong Windmill 115 

The Leffel Windmill , 119 



Xll CONTENTS. 

CHAPTER VIII. 
EXPERIMENTS ON WINDMILLS. 

PAGE 

No reliable American experiments 122 

Smeaton's experiments 123 

Details of method 124 

Table VI., showing results of Smeaton's experiments 125 

Smeaton's maxims 126 

Discussion of Smeaton's results 127 

Coulomb's experiments 128 

Description of mills experimented on by Coulomb 129 

Details and results of Coulomb's experiments 130 



CHAPTER DC 

THE CAPACITY AND ECONOMY OF THE WINDMILL. 

The standard of economy 132 

The current expense of prime movers 133 

The capacity of the windmill 134 

The horse-power of windmills 135 

Table VII., showing capacity of the windmill » . . 136 

Economy of the windmill 137 

Table VIII., showing economy of the windmill 138 

The economy of steam-pumps 139 

Relative economy of the windmill and steam-pump 139 

Table IX., showing economy of steam-pumps 140 

Tankage required for windmills 142 

Its effect on the economy of windmills 143 

The economy of the windmill and Ericsson's hot-air engine com- 
pared 143 

Table X., showing economy of Ericsson's hot-air engine 144 

Relative economy of the windmill and the gas-engine 144 

The windmill the most economical prime mover 145 



CONTENTS. Xlll 

CHAPTER X. 

USEFUL DATA IN CONNECTION WITH WINDMILL PRACTICE. 



PAGF 



Allowance for friction of water in pipes 146 

Table XL, showing loss by friction of water in pipes 149 

Table XII., showing co-efficient of friction in axles 150 

Table XIII., showing capacity of windmill pumps of different diame- 
ters and strokes 151 

Table XIV., showing class and proper diameter of pumps .... 152 

Table XV., showing number of acres irrigated by windmills .... 153 

Table XVI., showing capacity of cisterns and tanks 153 

Table XVII., showing dimensions, weight, etc., of wrought-iron pipes, 154 

Index • 156 



THE 



WINDMILL AS A PRIME MOVER. 



INTRODUCTION. 

THE USE OF THE WINDMILL. 



The following questions have been frequently asked 
by those interested in the study of windmills : " Why are 
not windmills more generally used ? " " Should they not 
have an economic use ; for example, to pump water ? " 

These questions, in various forms, but always to the 
same intent, have been propounded, not only by laymen, 
but even by professional engineers of noted ability and 
wide experience in their specialties. The invariable 
answer of the author has been to the effect, that in 
truth windmills are not only economical prime movers for 
specific purposes, but that such application and economy 
are, in fact, better appreciated to-day than they have ever 
been before ; in other words, that there are more wind- 
mills in use at the present time than at any other period 
in the history of the world. 

To place the number of windmills at work in Amer- 
ica at several hundred thousand, is to give an estimate 



... • • 



2 THE WINDMILL AS A PRIME MOVER. 

which those who have been interested in this department 
of engineering, and who have travelled along the main 
railroad lines of the country, must pronounce as low. 
And when we further learn that in some single cities of 
the Union over five thousand windmills are manufac- 
tured, on an average, each year, it'does seem remarkable 
that so general a lack of acquaintance with the fact of 
their extended use should be the rule with so many 
otherwise well-informed and observant men. 

That this is due to an impression that windmills 
must be antiquated, from the nature of things, there 
can be no doubt. There was a time when the natural 
forces of wind and water were the only ones at the 
command of man for industrial purposes, and when the 
motors driven by these forces monopolized all indus- 
trial pursuits which man did not accomplish by his own 
physical exertion. Then came the recognition of the 
value of steam as a motive power ; and the era of Watt 
practically introduced the steam-engine, with its great 
amount of power concentrated in a small weight and 
volume, with its reliability of action and its close regula- 
tive qualities. This was certain to speedily and effec- 
tively take the place of windmills in many industries. 
Independent of the fact that it enabled the creation of 
the most startling and important innovations, — such, for 
instance, as railroad traffic, and a host of others that 
wind and water motors did not permit, — its extended 
use, its concentrated power, and its unceasing action 
gave an appearance, in the popular mind at least, of 



INTRODUCTION. 3 

unreliability, clumsiness, and smallness of power, to wind 
motors, sufficient to account for the general misappre- 
hension under discussion. 

Though the advent and general application of steam 
replaced the windmill in many of its strongholds, and 
restricted its use to a few specific purposes, such use 
has become a very extended one, and will be still further 
enlarged in the near future, as the true value of the 
windmill as a prime mover becomes better appreciated, 
and as electrical storage batteries become more of a 
success. 

For certain specific purposes, and, primarily among 
them, for pumping water in moderate quantities, the 
windmill is not only a thoroughly reliable, but at the 
same time the most economical * prime mover, and, as 
far as judgment can now be passed, will hold this place 
for many years to come. 

The power purposes which windmills are specially 
fitted to subserve are circumscribed and defined by the 
character of the motive fluid, wind. Though the wind 
may be relied upon to blow with sufficient velocity to 
drive a windmill to its average working capacity eight f 
hours a day, it is evident that there are minutes and 
hours of total calm.J 

Therefore the employment of the windmill is re- 
stricted to two classes of use : — 

* See chap. ix. p. 132. 
t See pp 8, 136. 
t See p. 8. 



4 THE WINDMILL AS A PRIME MOVER. 

I. To Work of that Nature which admits of a 
Suspension during a Calm. 

For instance, to work on a farm, such as shelling 
corn and cutting feed, driving small sawmills, and the 
like. 

II. To Work where Accumulated Power can be 
Stored for Future Use. 

Under this caption the windmill has its main use, and 
three specific applications at once suggest themselves. 
The first is that which now claims the extended employ- 
ment of windmills. 

1 . For pumping and storing water. A few special 
adaptations of this use may be mentioned. Water is 
supplied to country houses and farms, to manufacturing 
establishments, and to the upper stories of office build- 
ings and domestic dwellings, when the pressure in the 
reservoir is not sufficient to effect this; railway water 
stations and tanks are supplied with water; and dry 
lands are irrigated. 

(Sand has also been raised, in place of water, and 
has been applied to the driving of an overshot wheel.) 

2. For compressing and storing air. 

3. For driving dynamo-machines to charge electrical 
accumulators. This was first suggested in 1881 by Sir 
William Thomson. The application of the windmill to 
this purpose will soon come actively into play when 
storage batteries have been developed to a greater 
success than is attained at the present time. 



WIND: ITS VELOCITY AND PRESSURE. 



CHAPTER I. 

wind: its velocity and pressure. 

In the treatment of this interesting topic, we have 
in the main restricted ourselves to a consideration of 
those data of importance in the theory and practice 
of windmill construction and use. It is expedient to 
mention this at the outset; inasmuch as this chapter 
makes but slight mention of the effect of wind on other 
than plane surfaces, and is therefore of but slight value 
to those who are in search of information about the 
effect of wind on bridges, in which the members are 
curved and of complicated shapes. 

In fact, the knowledge extant of the effect of wind on 
other than plane surfaces is scanty, and on the whole con- 
flicting. Undoubtedly, further experiments are needed 
to definitely settle the problem of wind pressure on plane 
surfaces ; still, knowledge as to this particular is far more 
accurate than is that relating to the wind pressure on 
curved surfaces. This is evident from the records of 
experiment, and the opinions of those authorities who 
have given the matter their attention. 

Definition of Wind. — When the density of air is 
uniform throughout, the atmosphere remains at rest ; but 



6 THE WINDMILL AS A PRIME MOVER. 

as soon as this equilibrium is destroyed, a movement 
results which takes the name of wind. If in one part 
of the atmosphere the air becomes more dense, it rushes 
towards that part whose density is less, in the same 
manner that the air compressed in a pair of bellows 
escapes by its orifice. These currents of air are caused, 
directly or indirectly, by differences of temperature at 
different times and localities, giving rise to changes of 
density, and varying the production and condensation 
of watery vapor. 

Average Movement and Velocity. — Through the 
courtesy of the chief signal-officer of the army, we are 
enabled to present the following statement, showing the 
average monthly movement of the wind, in miles, at 
the below-named stations of the Signal-Service, United 
States Army (computed and compiled from the records 
on file at the office of the chief signal-officer of the 
army). 



WIND: ITS VELOCITY AND PRESSURE. 



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No. of Years* 
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Average* per 
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8 THE WINDMILL AS A PRIME MOVER. 

It has been found by experience, that it requires, oh 
an average, a wind of a velocity of six miles per hour 
to drive a windmill, and that the latter will run, on 
an average, eight hours per day. From this it is safe 
to assume that one-third the total movement of the 
wind is lost, as far as the work of the windmill is con- 
cerned, and the rest distributed on the eight hours of 
work. Then, dividing s?6g x 2 = 3846 by 30 X 8 = 240, 
we find the average velocity of wind, during the eight 
hours of work of the windmill, to be equal to ^, or 16 
miles per hour; or, 16 X 1.46-= 23.5 feet per second. 

Relation between Pressure and Velocity of Wind. — 
In 1876* the author published the following method 
of finding the pressure corresponding to a given velocity 
of wind, when the wind impinged upon a plarte surface 
perpendicular to its course. It differed from other 
methods more especially in taking into account the 
effect of temperature. As will be seen farther on, a 
variation in temperature from o° to ioo° F. produces a 
difference in the amount of pressure for a given velo- 
city, of over one-fifth the total amount. In making the 
computations for a correct table, attention was paid to 
the following facts : — 

That the pressure depends upon both the velocity 
and the density of the air; that this density depends 
upon the temperature, the barometric pressure, and the 
pressure due to the motion of the air. 

* Engineering and Mining Journal, Sept. 23, 1876. 



WIND: ITS VELOCITY AND PRESSURE. 9 

Let p = barometric pressure, in pounds per square foot, at any level, 

temperature of air being 32 F., absolute temperature t t = 

491.4 degrees; 
P = pressure, in pounds per square foot, due to the motion of the 

air; 
A = barometric pressure (average) at the level of the sea ; 
d x = density of air under pressure p + P when t x = 491.4 

degrees ; 
d 2 = density of air under pressure p x when t x = 491.4 degrees ; 
d = density of air under pressure / + P, the air being at any 

absolute temperature /. 

Then 4 = ( ' + />) * and , . G» + *H X 4 

A A x / v ' 

It has been found by experiment, that, for/ x = 21 16.5 
pounds per square foot, and /, = 491.4 degrees (32 
F.), d 2 = 0.080728 pound. Substituting these values 
in equation (1), 

o.oi8 7 43(/-f-/ ? ) /TX 

d= . (I.) 

Let c = velocity of the wind, in feet per second ; 

Q = volume of air carried along per square foot in one second ; 

d =s density of air, as found above ; 

g = velocity, in feet per second, generated by gravity ; 

P = pressure of wind per square foot of surface. 

Then P = — . (2) 

Q = c cubic feet per second ; therefore, from equation 

d* 

*-7 (IL) 



IO THE WINDMILL AS A PRIME MOVER. 

Substituting value of d from equation (I.) into equation 
(II.) i we h ave 



0.018743(1 + P)* , . 

^= £ > (3) 



therefore 



p x 0.018743 
— - 0.018743 



(III.) 



By substitution of values for the velocity c y the baro- 
metric pressure at 32 F. for /, and the temperature 
expressed absolutely for / in equation (III.), the theo- 
retical pressure corresponding to these values is readily 
ascertained. Now, some of this pressure is lost by fric- 
tion of the particles of air in motion, so that the pres- 
sures found from equation (IIL) must be multiplied by a 
co-efficient to make them identical with actual pressures. 
To determine this co-efficient (or the ratio of the actual 
pressure to the theoretical) , a series of observations were 
made, in which the actual pressure of wind, its velocity, 
the temperature, and the barometric pressure, were 
recorded at the same time. The co-efficient thus deter- 
mined was 0.93. While exercising all care possible at 
the time to insure accurate results, the methods used 
were not such as to meet the author's entire satisfaction 
at the present date ; and this co-efficient is therefore 
given with some degree of reservation, though it is 
deemed to be not far from correct. Until more accurate 
experiments shall have been made, it will be safe to use 
this co-efficient in calculations for practical work. Multi- 



WIND: ITS VELOCITY AND PRESSURE. II 

plying equation (III.) by this co-efficient, we find equa- 
tion (IV.), from which, by substitution of proper values 
for p, t, and c, we can calculate P x = the actual pressure 
corresponding to these values, 

— — -0.018743 

When p = 2 1 16.5 pounds per square foot = average 
atmospheric pressure at the level of the sea, 

r 36.892887 ■ 

0.018743 

By substitution in equation (V.) the following table 
(Table II.) has been constructed. For any other baro- 
metric pressure, the figures in Table II. must simply 
be multiplied by the ratio of this barometric pressure 
reduced to its value for temperature of air = 32 F. to 
2 1 16.5. Thus, letting p z = barometric pressure at any 
absolute temperature /, then p = ^£j, and the table 
must be multiplied by j~^> 



12 



THE WINDMILL AS A PRIME MOVER. 



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WIND: ITS VELOCITY AND PRESSURE. 



13 



53 



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THE WINDMILL AS A PRIME MOVER. 



The relation between the pressure and velocity of 
wind given above corresponds quite closely, when the 
temperature is at about 45 F., with the following table, 
originally communicated by Mr. Rouse to Smeaton, and 
now quite generally adopted for ordinary calculations. 



TABLE III. 

THE ROUSE-SMEATON TABLE OF WIND PRESSURES. 



Velocity 


of the Wind. 


Pressure. 


Common Appellations of 








Miles per 
Hour. 


Feet per 
Second. 


Per Square 

Foot, 
in Pounds. 


Force of Wind. 


I 


I.47 


0.005 


Hardly perceptible. 


2 

3 


2.93 
4.40 


O.020 
O.044 


[ Just perceptible. 


4 
5 


5.87 
7.33 


O.079 
O.123 


[ Gentle, pleasant wind. 


10 
15 


14.67 

22.00 

• 


O.492 ' 
1. 107 


[ Pleasant, brisk gale. 


20 
25 


29-34 
36.67 


1.968 
3-075 


[ Very brisk. 


30 
35 


44.01 
5J-34 


4.429 
6.027 


> High wind. 


40 


58.68 


7-873 


1 


45 


66.01 


9-963 


> Very high storm. 


50 


73-35 


12.300 


J 


60 


88.02 


I7-7I5 


Great storm. 
( A hurricane that tears up trees, 


80 


117.36 


31.490 


< carries buildings before it, 
I etc. 


100 


146.70 


49.200 


Immense hurricane. 



WIND: ITS VELOCITY AND PRESSURE. 1 5 

The formula which, in its general form, applies alike 
to Tables II. and HI., is P = — , equation (II.); or, for 
45 temperature, P = 0.005^, equation (VI.), in which c 
is velocity in miles per hour. 

Inasmuch as the correctness of this formula has been 
questioned by some engineers of standing, who have 
maintained that the pressure is equal to — (— being 
equal to h\ it is well to quote the following authorities 
in support of the analysis given above : — 

Weisbach (" Mechanics of Engineering," edition of 
Eckley B. Coxe, 1882, p. 1030, §510), presenting the 
formula P = C— Fy, equation (VII.), in which £ denotes 
an empirical number dependent upon the shape of the 
surface, says this " general formula for the impulse and 
resistance of an unlimited stream is also applicable 
to the impulse of wind and to the resistance of the 
airr 

In §511 we learn, that, "according to Du Buat's 
experiments, and those of Thibault, we can put, for 
the impulse of water and air against a plane surface at 
rest, £ = 1.86." It will be noted that this co-efficient 
substituted in equation (VII.) gives the expression 
P = 0.93-/% or the same co-efficient, 0.93, by which 
equations (II.) and (III.) were multiplied to obtain the 
figures in Table II. In vol. ii. (edition of Du Bois, 
p. 652, § 342) Weisbach again gives the value of P as 
equal to 1.86^/^7, and continues, "or, since - = 0.0155, 
P = 0.028830^/^ ; or, if we take the density of the 



1 6 THE WINDMILL AS A PRIME MOVER. 

wind, y = ^ = 0.078125 pounds, P = 0.002252s' 2 / 7 : 
therefore, if the area of the surface is one square foot, 
the pressure of the wind is P = 0.0022522/* pounds." 

v, in the above expression, equals feet per second. 
Remembering that 1 mile per hour equals 1.46I feet 
per second, the pressure of the wind, when c equals 
miles per hour, becomes 

P= 0.002252 x 1.46$ x 1.46$**, 
or 

P = 0.005* 9 , 

same as equation (VI.). 

Rankine (" A Manual of the Steam-Engine and 
other Prime Movers," edition 1874, p. 163, § 144) 
says, — 

"The direction and amount of the pressure exerted by a jet or 
stream of water [or of wind — A. R. W.] against a solid surface are 
determined by the following principles, which are the expression of the 
second law of motion as applied to this case : — 

"1. The direction of that pressure is opposite to the direction of 
the change produced in the motion of the stream during its contact 
with the surface. 

" 2. The magnitude of that pressure bears to the weight of water 
flowing along the stream in a second, the same ratio which the velocity 
per second of the change in the motion of the stream bears to the 
velocity generated by gravity in the second [viz., g = 32.2 feet per 
second]." 

On p. 164 the magnitude of the pressure is expressed 
by — — , in which DQ\s the weight of the flow of water 



WIND: ITS VELOCITY AND PRESSURE. I J 



in a second, and HC represents the velocity of the 
change of motion undergone by the jet during its contact 
with the vane. When the vane is at rest, then HC 
equals the original velocity of the jet c, and Rankine's 
formula becomes 



n DQc n Dc* 

P= —=- or P= — > 
g g 



same as equation (II.). 

Mr. T. Hawksley, past president Institution of Civil 
Engineers (" Proceedings of the Institution of Civil En- 
gineers," vol. lxix., 1882), referring to the pressure of 
wind upon a fixed plane surface, maintained that the 
general solution of the problem might be thus briefly 
stated : — 

" Let v = velocity of the current in feet per second ; 

h = the height through which a heavy body must fall to produce 

the velocity of v ; 
w = the weight, in pounds, of a cubic foot of the impinging fluid 

[for atmospheric air, about 0.0765 pounds j ; 
g = 32, the co-efficient of gravity. 



1? 
" Then h = — ; and since /, the pressure of a fluid striking a plane 

surface perpendicularly, and then escaping at right angles to its original 
path, was that due to twice the height h (D'Aubuisson de Voisins* 
Hydraulics, Rouse's Experiments), then 

wv 1 I „ . . . \ 0.0765^ (v\* . „ 

p = = I for atmosphenc air J = f — 1 very nearly," 



1 8 THE WINDMILL AS A PRIME MOVER. 



or ^-zf very nearly ; or, if c equals miles per hour, 



P = or — c* nearly, 

400 200 J§ 



which is again equivalent to equation (VI.). 

Mr. Rogers Field, in the same discussion (" Pro- 
ceedings of the Institution of Civil Engineers," session 
1881-82, vol. lxix.), agreed with the above presentation 
of Mr. Hawksley, but said that " this could not, of course, 
be strictly accurate, because other factors must enter the 
question, such as the density of the air, which would be 
affected by the temperature of the air and the height 
of the barometer." 

It should be remarked, that the analysis and Table II. , 
presented on pp. 8-13, originally communicated by the 
author in 1876, take account of the very factors which 
Mr. Field mentions. 

Professor Jules Gaudard, in his paper on " The 
Resistance of Viaducts to Sudden Gusts of Winds" 
(" Proceedings of the Institution of Civil Engineers," 
vol. lxix., 1882), makes an analysis of the pressure of 
wind, finds the same equal to P = —s sin a, and says, 
" As - is double the height which the column of water 
would require to fall to attain a velocity v at the bottom 
of fall, it follows that the dynamical pressure, in the 
case of vertical incidence, may amount to double the 
weight of the same column in a state of rest." In a joint 
discussion of his own paper and that of Mr. Charles 



WIND: ITS VELOCITY AND PRESSURE. 19 

B. Bender, Professor Gaudard said he " would come back 
to the theory given in various treatises on mechanics, 
such as Mr. Bresse's ' Hydraulique ' (p. 311 of the i860 
edition), which theory, based on the extinction of the 
amount of motion by the re-action of the ground, re- 
sulted in representing the theoretical pressure by double 
the height of the fall. The total dynamic effect should 
really be more powerful than the simple weight of a fluid 
column at rest: the rate of flow played an important 
part. On the other hand, it should be remembered, 
that the theory disregarded viscosity, the mutual shocks 
of the liquid molecules during their fall, the clashing of 
their motion inducing either vacuums or an admission 
of air, — all constituting disturbing causes, which doubt- 
less notably modified the action, and rendered it neces- 
sary to leave the last word on this subject to the result 
of experience." True as are these remarks of Professor 
Gaudard, it should be observed, that, when the fluid is 
air, the disturbing causes of molecular action, viscosity, 
and the like, will not represent a very large percentage 
of the theoretical dynamic effect. 

Dr. William Pole, in the same discussion, figured 
the theoretical pressure as only one-half the amount 
given above, considering the dynamic pressure equal to 
the statical weight of a column whose height equals -, 
but added, that " there appeared reason to think, that, 
when the force of the wind was actually received on flat 
surfaces, the pressure was considerably in excess of these 
amounts." 



20 THE WINDMILL AS A PRIME MOVER. 

All of the above tends to give strong support to 
the analysis presented on pp. 8-13; but there is one 
great authority differing from the same, whose work is 
deserving of the highest consideration and credit, and 
the results of whose scientific observations, throwing 
some doubt on the accuracy of the above analysis, should 
be noted here. 

Hagen* (Berlin, 1874) gives, as the result of very 
careful observations of wind of moderate velocities, the 
following formula, 

P= (0.0028934 •+ o.oo\40$p)SV 2 9 

in which P = total pressure in pounds avoirdupois, 
p = the outline or perimeter of the exposed surface in 
feet, V = velocity in miles per hour, S = area in 
square feet. The formula applies to plane surfaces (of 
no considerable depth) placed normal to the incident 
wind, and with the density of the air corresponding to a 
barometric height of 29.84 inches and a temperature of 
59 F. If S = 1 square foot, s p = 4, and Hagen's for- 
mula becomes 

P= 0.0035949 F*; 

while for 6o° F., Table II. shows 

P= 0.004750 P*, 

or, the pressure obtained experimentally by Hagen is 

* Appleton's Cyclopaedia, article Wind, by Professor Cleveland Abbe. 



WIND: ITS VELOCITY AND PRESSURE 21 

over twenty-five per cent less than that recorded in 
Table II. 

Thus, while for the time being, adopting the analysis 
and values recorded on pp. 8-13, supported by the 
authority of D'Aubuisson de Voisin, Bresse, Weisbach, 
Rankine, Hawksley, Field, and Gaudard, we feel that 
the same must be experimentally verified before being 
finally accepted as correct ; and we note that the careful 
scientific observations of one of the greatest specialists 
(Hagen) give results differing considerably from the 
data provisionally adopted. It remains to be seen 
whether future experimental evidence will support these 
results, or the formula given by Hagen. 

Velocity of Wind as affected by Height of Observa- 
tion. — Mr. Thomas Stevenson, member of Institution of 
Civil Engineers (" Journal of the Scottish Meteorological 
Society," 188 1), finds that the velocity of the wind varies 
with the height above the surface of the ground, and 
proposes the following formula for finding the velocity, 
V, at any height, H (in feet) , v equalling the velocity at 
the standard height of fifty feet above ground : 



y.JZ±Jl. 

▼ 122 J 

for one hundred feet above the ground, 



▼ 122 
or nearly i.2z>; for twenty-five feet above the ground, 



22 THE WINDMILL AS A PRIME MOVER. 



▼ 122 

or nearly o.gv. 

This range of twenty-five and one hundred feet, or 
of i.2# and 0.9^, constitutes the limits between which 
Mr. Stevenson's formula may be said to apply to wind- 
mill practice. 

Professor E. D. Archibald ("Nature," No. 786) 

records experiments on the velocity of wind at different 

heights, by means of Biram's anemometers raised by 

kites. His results favor the formula £ = (y) K , while 

Mr. Stevenson's formula for heights above fifty feet is 
v ___ /H\% 

v — \h) ' 

High Wind Pressures. — Since windmills are, of 
course, preferably located where they are most freely 
exposed to the action of the wind, and since they 
must be made strong enough to withstand the pressure 
of the heaviest gales, information as to the highest velo- 
cities and pressures attained becomes of interest. 

Mr. R. H. Scott,* then secretary, now president, of the 
Scottish Meteorological Society, estimates the velocity of 
the wind in the greatest hurricane at 90 miles an hour. 
Mr. C. B. Bender f states that the greatest progressive 
motion of an Atlantic hurricane having been observed to 
be 50 miles per hour, and no change of direction taking 



* Quarterly Journal of the Meteorological Society, 1874, vol. ii. p. 109. 
t Proceedings of the Institution of Civil Engineers, vol. Ixul, session 
1881-82. 



WIND- ITS VELOCITY AND PRESSURE. 23 

place, it may be assumed that the velocity of the wind 
proper at its maximum was not more, or much more, than 
100 miles per hour. Professor Jules Gaudard* quotes 
Rankines statement, that about 55 pounds is the greatest 
wind pressure observed in England by anemometers or 
dynamometers, which is confirmed by the fall of chimneys 
and other buildings, and remarks that a pressure of 61 
pounds on the square foot was recorded at Liverpool 
during the storm of the 7th of February, 1868, and of 71 
pounds on the 27th of September, 1875. ^ n regard to the 
highest wind pressures in France, M. Gaudard mentions 
the upsetting of a train between Narbonne and Perpi- 
gnan, in December, 1867, as indicating a pressure between 
30 pounds and 50 pounds, and other similar accidents 
with empty wagons on the same railway, in February, 
i860, and January, 1863, as indicating a pressure of from 
2 5 to 33 pounds. He continues : " No other part of 
France is exposed to such violent storms ; nevertheless, 
in considering the stability of lighthouses, Fresnel allowed, 
for the possibility of wind pressures up to 56 pounds." 
Trautwine f mentions the breaking of a gauge at Girard 
College, Philadelphia, under a strain of 42 pounds per 
square foot ; a tornado passing at the moment within a 
quarter of a mile. At the Central Park (New York) Ob- 
servatory, in March, 1876, a wind of 28.5 pounds per 
square foot pressure was noted, and on Feb. 26, 1886, the 
greatest single gust was recorded, viz., 37.5 pounds per 

* Proceedings of the Institution of Civil Engineers, vol. brix., session 
1881-82. t The Civil Engineer's Pocket-Book. 



24 THE WINDMILL AS A PRIME MOVER. 

square foot. On Mount Washington, N.H.,* 180 miles 
per hour has been observed. Mr. C. Shaler Smith f gives 
the following as the most violent storms of which he has 
personal record, having visited the tracks of many destruc- 
tive storms as soon as possible after their occurrence : — 

"First, East St. Louis, 1871 : Locomotive overturned ; 
maximum force required, 93 pounds per square foot. 

" Second, St. Charles, 1877 : Jail destroyed; force re- 
quired, 84.3 pounds per square foot. 

" Third, Marshfield, Mo., 1880: Brick mansion-house 
levelled ; force required, 58 pounds per square foot 

"Fourth, Havre de Grace, Md., 1866 : Ten spans of 
wooden Howe truss bridge, 250 feet each, blown over ; 
force required, 27 pounds per square foot. 

"Fifth, Decatur, Ala., 1870: Two spans of combina- 
tion triangular truss blown over; force required, 26 
pounds per square foot. 

" Sixth, Meredosia, 111., 1880 : One span wooden 
Howe truss, 150 feet long, overturned ; force, 24 pounds 
per foot. 

"Seventh, Omaha, Neb., 1877: Two spans iron Post 
truss, 250 feet each, blown down ; force required, 18^ 
pounds per square foot." 

Mr. Smith, in the same paper, also presents the fol- 
lowing table of "the highest pressures registered in Great 
Britain, those recorded by Mr. Hartnup at the observa- 
tory at Bidstone : " — 

* The Civil Engineer's Pocket-Book. 

f Transactions American Society of Civil Engineers, vol. x., May, 1881. 



WIND: ITS VELOCITY AND PRESSURE. 



25 



TABLE IV. 



Date of Observation. 


Greatest Velocity, in 

Miles, between any 

Hour and the Next 

Hour Following. 


Greatest Pressure 

in Pounds on the 

Square Foot 


27th December, 1868 . . . 
13th October, 1870 . . . 
9th March, 1871 .... 
27th September, 1875 . • • 
23d November, 1877 . • • 
28th December, 1879 . . . 


92 
82 

79 
8i 
80 
59 


80 

65 
90 

70 

64 

38 



While such high pressures as above recorded are ex- 
ceptional, their enumeration may serve to point out the 
necessity of windmills being so constructed as not only 
to run under light winds, but also to possess sufficient 
strength to withstand heavy gales. And equal care, in 
this particular of strength to withstand heavy wind press- 
ures, should be observed in the design and construction 
of windmill towers, which are at times of great height 
and comparatively small weight and base. 

The conclusion that some of the pressures here noted 
are in all probability higher than have actually occurred, 
or do occur, is rendered plausible by reference to certain 
experiments detailed by Mr. Benjamin Baker, the engi- 
neer of the Forth Bridge, in a paper read by him before 
the British Association for the Advancement of Science, 
at Montreal, 1884. Mr. Baker, while engaged in the 
erection of the Forth Bridge, obtained simultaneously the 
records of wind pressures, as denoted by two small fixed 



26 THE WINDMILL AS A PRIME MOVER. 

pressure gauges i± square feet area, by one large fixed 
gauge 300 square feet area, and by one revolving gauge 
or anemometer. Two years' records showed that " the 
effective pressure per square foot on a large and com- 
paratively heavy board averages only about two-thirds 
of that indicated by an ordinary light anemometer." 
Furthermore, during the two years' record, there was 
noted but a single extraordinary and exceptionally high 
wind pressure, viz., 65 pounds, recorded by the revolving 
anemometer, " the index being at the end of its travel " 
at the time. Mr. Baker thereupon experimented with 
the gauge, and finally, in the presence of the inspecting 
officers of the Board of Trade, made it register 65 
pounds by the sudden application of pressure not exceed- 
ing 20 pounds. In the language of Mr. Baker, " the 
momentum of the light index needle, and not that of the 
pressure plate which was bridled back, sufficed to cause 
the error." He therefore considers the record of 65 
pounds as valueless so far as the specific maximum press- 
ure obtained during the great storm is concerned, but of 
considerable value as evidence that the highest pressure, 
whatever it might have been, partook of the character 
of a smart jerk of too instantaneous duration to affect a 
structure of any size or weight. Mr. Baker concludes 
from his experiments that a larger board shows a smaller 
average pressure per square foot than a small one, that 
" the records of anemometers as at present obtained are 
utterly misleading and valueless for all practical pur- 
poses," and finally asserts that both Mr. Fowler and he, 



wind; its velocity and pressure. 27 

the engineers of the Forth Bridge, " are of opinion . . . 
that the assumed pressure of 56 pounds per square foot 
(recommended by a committee of the Board of Trade, 
after investigating the Tay Bridge disaster, as ' the maxi- 
mum wind pressure to be provided for ') is certainly in 
excess of any thing likely to be realized." 

In view of all that has preceded, it is safe for the 
present to accept as a fact, in the design of exposed 
structures in America, England, and France, that an 
allowance for a wind pressure of 56 pounds per square 
foot will be ample ; or, in other words, any structure 
exposed to the action of 'the wind should be so designed 
as to have, adequate strength to successfully resist a wind 
pressure of 56 pounds per square foot. 



28 



THE WINDMILL AS A PRIME MOVER. 



CHAPTER II. 

THE IMPULSE OF WIND ON WINDMILL BLADES.* 

Let AB (Fig. i) = c represent the direction of mo- 
tion and the velocity of the wind ; the latter in feet per 
second. Let BC = v, perpendicular to AB, represent 
the direction of motion and the Velocity of any element of 




Fig. i. 

the sail ; the latter in feet per second. AB is 1 to B C, 
because the direction of motion of each point of the 
surface of a windmill sail is perpendicular to that of the 
wind. Then, the wind moving in the direction AB with 

* The main portion of this chapter, was originally presented by the author in 
"A Dissertation on the Theory and Practice of Windmills," Engineering and 
Mining Journal, Oct. 7 and 14, 1876. 



THE IMPULSE OF WIND ON WINDMILL BLADES. 29 

a velocity c y and the element of the sail moving in a 
direction B C with a velocity v y the effect of these com- 
bined motions would be the same as if, the air being at 
rest, the sail moved in a direction BD with a velocity 
equal to BD = (r* + if) 1 ; or, as if the wind moved 
in a direction BD and struck the sail with a velocity 
(c 2 + 2/)*, the sail being at rest. 

Let the angle of impulse < ABB = a, let < DBA 
= D; 

then < DBE = a — D, 

sin(<* — D) = sinacos/? — sinZ>cosa. 

AB = DBco&DBA .-. (** + **)* = r sec Z>. 

Let (? = quantity of wind, in cubic feet, flowing along per square foot 
per second ; 
d = density of wind ; 
k = 0.93 = co-efficient of friction of particles of air in motion 

* (see p. 10) ; 
S = surface of sail in square feet ; 

F = total pressure, in pounds, exerted by the wind normally to 
the surface. 

F = ^0?^ + *)isin(« - D). 
g 

Substituting for Q its value c % 

SKcd 

F = c sec D (sin * cos Z> — sin Z? cos a) : 

g v ' 

„ SKcdc, . ^ x ^ v 

F= (sina — tan Z> cos a): tan// = -z 

g v * 

.*. ^*=s (sin« cos a). 

g v c ' 



30 THE WINDMILL AS A PRIME MOVER. 

To find what part of this pressure is useful in causing 
rotation, we resolve it into two components, one perpen- 
dicular to, and the other in the direction of BC. The 
former produces no beneficial effect; on the contrary, 
increases the pressure on the journals, and thus gives 
rise to a loss of effect by friction. The component in 
the direction BC, however, is that part of the pressure 
exerted which is entirely utilized, and represents the use- 
ful pressure on the sail. Let this pressure be represented 

by Z. Then L = jF cos a = (sin a — "cos a) cos a. 

This multiplied by v, the velocity of the sail in feet per 
second, gives for the theoretical mechanical effect of the 
windmill sail, 

T SKc*d I . v \ /T x 

Lv = J sin a cos a ] cos-a. (I.) 

Rankine, in his " Steam-Engine and other Prime 
Movers," edition 1874, p. 170, finds the following value 
for the theoretical mechanical effect due to the impulse 
of water on a flat vane : 



DQvc ^ cos f cos 8 — ^cos a 8 



When applied to windmills, it must be remembered that 
the direction of motion of each point of the sail is per- 
pendicular to that of the wind, and the following substi- 
tutions can accordingly be made : 

8 ss 90 — i /• cos 8 = sin£; 



THE IMPULSE OF WIND ON WINDMILL BLADES. 

and, since 

a ss 8, a = 90 — & 

.\ £ = 90 — a .*. sin f = cos a, cos f = sin a. 

DQcv sin a cos a — v* cos* a . 



31 



/>z> = 



^ 



and, substituting L for />, 6* for the area of surface in 
square feet, and kcd for QD, " the weight of water flow- 
ing along the stream per square foot in a second," 



Z* = 



Skdc* 



1 I • v \ 

visma — -costf J cos a, 



which is the same as formula (I.), found directly as 
above. 

Weisback deduces (see "Weisbach's Mechanics," 
edited by Walter R. Johnson, p. 354) a value for the 
theoretical mechanical effect, of which the errors in solu- 
tion can be best pointed out by quoting a passage : — 

" If c = the velocity of the sail, Q = the quantity of wind striking 
on CD per second, y = the density of the wind, and a = the angle CAH 




IIP 



Fig. 2. 

(Fig. 2) which the direction of the wind makes with CD, then, on the 
assumption that the plane moves away in the direction of the wind, 
the normal impulse of the wind on CD is N = ^-^sin aQy. Putting 



32 THE WINDMILL AS A PRIME MOVER. 

the section CN = G, then the quantity of wind Q coming into action is 
not Gc, but G(c — v), as the sail moving, with the velocity v leaves a 
space Gv behind it, which takes up a proportion of the quantity of wind 
Gc following it, equal to Gv, without undergoing any change of motion. 
Hence the normal impulse may be put N = c - — - sintf(*r — v)Gy = 
^ — ^- sin a Gy ; or, if F = area of the element CZ?, and we substitute 
-Fsintf for £, then N = - — ?L s i n 2 0/^. Besides this impulse on the 
face of CD, there is a counteraction on the back, inasmuch as one part 
of wind passing in the direction CE and DF, at the outside of the 
plane, takes an eddying motion to fill up the space behind, and conse- 
quently loses pressure corresponding to the relative velocity (c — v) sin a, 
and represented by ilZil sin 2 aFy. If we combine these two effects, 
we get the normal impulse on the element of the sail." 

On examination, it will be seen that the relative 
velocity of c and v, i.e., the fact that while the wind is 
moving with a velocity c, the sail moves with a velocity v> 
and therefore the wind actually strikes the surface with 
a velocity (c — v) y is erroneously allowed for, twice. In- 
stead of the normal impulse N reading N= (<: sin aG y> 
- it ought to read N = ^— ^ c sin a Gy : for, in deriving 
the expression N =• Cjz ^- sin a, the fact of the quantity of 
wind striking with a relative velocity {c — v) is taken into 
account ; and it is a mistake to forget this, and to make 
the same allowance for a second time. Besides this im- 
pulse, Weisbach adds another term, which, as is explained 
below, it is not correct to add. He assumes correctly that 
the wind rushing past the sail produces a partial vacuum 
behind it, and that this must be replaced by air. But is 
it not probable that the vacuum will be filled up by wind 



THE IMPULSE OF WIND ON WINDMILL BLADES. 33 

of original velocity, and that the wind which has lost 
part of its velocity by impact, only tends to fill up the 
empty space left by the wind of original undiminished 
velocity? It is certain, that as soon as one "line" of 
wind has struck the surface, it glides along the surface 
with diminished velocity, and simply forms a moving 
cushion on the sail, upon which the wind, with its original 
velocity, impinges. These facts seem to us to challenge 
the correctness of Weisbach s analysis. 

From all of the above considerations, the author feels 
justified in adopting, as the theoretical mechanical ef- 
fect of a windmill sail, the expression 



Lv = v (sin a cos a ) cos a; (I.) 

pr \ c ' 



and, in finding the actual mechanical effect of a vertical 
windmill, merely to make a deduction for loss of effect by 
friction of the shaft, considering a vacuum to be formed 
behind the sail, and therefore assuming the resistance of 
the air to be equal to nothing. 

Best Angle of Impulse. — From formula (I.) it is ap- 
parent that the effect increases with the velocity c and 
with the area S, but it is not so evident how the angle of 
impulse affects the mechanical effect produced. That Lv 
may not be zero, sin a must be > - cos a, and cos a must 
be > O. If sin a > - cos a, tan a > - ; and, as cos a > O, 

c y c ' 7 

therefore a < 90 . There must, therefore, be a value of a 
between the limit tan a >- and a <90°, corresponding to 



34 THE WINDMILL AS A PRIME MOVER. 

a maximum value of Lv. To find the value, we solve the 
sin a — - cos a \ cos a tor a maximum by the 
laws of calculus, and obtain 



2# 

tan a a tan a = i, (II.) 



tan a = ? + y/i + Q*. (III.) 

In this formula, equation (2), 

a represents the angle of impulse of the wind upon the windmill blade 

(or sail), at any point of the blade, for maximum effect ; 
v = the velocity of the blade (at such point), in feet per second; 
c = the velocity of the wind, in feet per second. 

The table on p. 35 has been computed on the basis 
of equation (III.), and sets forth the best "angle of 
weather," that is, the angle which an element of the blade 
or sail makes with the plane of motion of the blade. 
This angle, which we will term w f is the complement of 
the best angle of impulse ; that is, w = 90 — a. 

Let / = total length of blade from centre of windmill shaft to outer ex- 
tremity of blade. 
v Q = velocity, in feet per second, of the blade or sail, at a distance 
^ / from the centre of the shaft. 

Then, in the table, w Q represents the best " angle of 
weather " at a distance \ I from the centre of the shaft, 
and w 19 w 9i . . . w 6 , represent the best " angles of weather'" 



THE IMPULSE OF WIND ON WINDMILL BLADES. 



35 



at distances $ /, f /, . . . /, respectively, from the centre of 
the shaft. 



TABLE V. 



SHOWING THE BEST ANGLES OF "WEATHER" FOR WINDMILL BLADES 
FOR GIVEN RELATIVE VELOCITIES OF BLADES AND WIND. 



v _ 
















c 


W = 


V) X = 


W 2 = 


7V 3 = 


W 4 = 


W S = 


W 6 = 




• / // 


/ // 


/ // 


/ // 


• / // 


• / // 


/ // 


O.IO 


42 841 


39 20 42 


36 39 1 


34 5 57 


3* 43 3 


29 3i 5 


27 30 14 


O.II 


4i 51 41 


38 47 47 


33 52 7 


33 7 3i 


30 35 4i 


28 17 15 


26 12 7 


O.Z2 


4i 34 44 


38 15 7 


35 6 2 


32 xo 46 


29 3i 5 


27 7 23 


24 59 6 


0.13 


41 17 48 


37 42 46 


34 20 49 


3* 15 5' 


28 29 17 


26 1 22 


23 50 46 


0.14 


4i 55 


37 » 44 


33 36 32 


30 22 32 


27 30 14 


24 59 6 


22 47 22 


0.15 


40 44 4 


36 39 1 


32 53 10 


29 31 5 


26 33 54 


24 23 


21 48 5 


0.16 


40 27 17 


36 7 40 


32 zo 46 


a8 41 25 


25 40 12 


23 5 4 


20 52 48 


0.17 


40 10 33 


35 36 40 


31 29 21 


27 53 31 


2* 49 4 


22 12 59 


20 I 15 


0.18 


39 53 53 


35 6 2 


30 48 56 


27 7 23 


24 23 


21 23 55 


19 13 '7 


0.19 


39 37 16 


34 35 47 


30 9 29 


26 22 57 


23 14 4 


20 37 43 


18 28 IO 


0.20 


39 20 42 


34 5 57 


29 3i 5 


25 40 12 


92 30 O 


19 54 10 


1746 8 


0.2X 


39 4 12 


33 36 32 


28 53 40 


24 59 6 


21 48 5 


X9 13 7 


17 6 47 


0.22 


38 47 47 


33 7 3i 


28 17 15 


24 19 34 


21 8 X3 


18 34 24 


16 29 56 


O.23 


38 31 25 


32 38 56 


27 4i 50 


23 41 35 


20 30 16 


17 57 5i 


15 55 21 


O.24 


38 15 7 


32 10 46 


27 7 23 


23 5 4 


19 54 10 


17 23 20 


15 22 53 


O.25 


37 58 55 


3i 43 3 


26 33 54 


22 30 


19 x 9 48 


16 50 42 


14 52 21 


O.26 


37 42 46 


3i 15 5i 


26 1 22 


21 56 18 


1847 3 


16 19 50 


14 23 36 
13 56 30 


O.27 


37 26 43 


30 48 56 


25 29 46 


ax 23 55 


18 15 52 


15 5o 35 


O.28 


37 10 44 


30 22 32 


24 59 6 


20 52 48 


x 7 46 8 


15 22 53 


13 3° 56 
13 646 


O.29 


36 54 50 


29 56 35 


24 29 18 


20 22 54 


17 17 46 


14 56 36 


O.3O 


36 39 1 


29 3i 5 


24 23 


19 54 10 


16 50 42 


14 3i 38 


« 43 54 


O.3I 


36 23 18 


29 6 2 


23 32 19 


19 3 6 32 


16 24 51 


14 7 55 


12 22 15 


O.32 


36 7 40 


28 41 25 


23 5 4 


18 59 58 


16 xo 


13 45 21 


12 1 43 


o-33 


35 52 7 


28 17 15 


22 38 38 


18 34 24 


15 36 33 


13 23 53 


11 42 14 


o.34 


35 36 40 


27 53 3i 


22 12 59 


18 948 


15 13 58 


13 3 25 


" 23 43 


0-35 


35 21 18 


27 3o 14 


21 48 5 


17 46 8 


14 52 2X 


12 43 54 


11 6 6 


0.36 


35 6 2 


27 7 23 


21 23 55 


17 23 20 


14 31 38 


12 25 l6 


10 49 20 


°-37 


34 50 53 


26 44 57 


21 O 28 


17 x 23 


X4 11 47 


12 7 29 


10 33 21 


0.38 


34 35 47 


26 22 57 


20 37 43 


16 40 13 


13 52 45 


II 50 28 


IO 18 12 


0-39 


34 20 49 


26 1 22 


20 15 37 


16 19 50 


13 34 30 


II 34 II 


10 3 32 


0.40 


34 5 57 


25 40 12 


19 54 10 


x6 xo 


13 16 57 


II l8 36 


9 49 37 


0.41 


33 5i 12 


25 19 27 


19 33 21 


15 41 " 


13 6 


II 3 40 


9 36 18 


042 


33 36 32 


24 59 ° 


19 13 7 


»5 22 53 


12 43 54 


IO 49 20 


9 23 33 


<M3 


33 21 58 


24 39 8 


18 53 29 


15 5 12 


12 28 19 


10 35 35 


9 11 20 


0.44 


33 7 3i 


24 19 34 


18 34 24 


14 48 8 


12 13 19 


xo 22 23 


8 59 37 


o.45 


32 53 xo 


24 23 


18 15 52 


14 31 38 


" 58 53 


10 9 42 


8 48 23 


0.46 


32 38 51 


23 4i 35 


17 57 5» 


*4 15 42 


« 44 57 


9 57 30 


8 37 35 


0.47 


32 24 48 


23 23 9 


17 40 21 


14 17 


11 31 32 


9 45 45 


8 27 12 


0.48 


32 10 46 


23 5 4 


17 23 20 


13 45 21 


11 18 36 


9 34 27 


8 17 13 


0.49 


3i 56 5i 


22 47 22 


17 6 47 


13 30 56 


11 6 6 


9 23 33 


8 7 37 


0.50 


3i 43 3 


22 30 


x6 50 42 


13 16 57 


10 54 3 


9 13 3 


7 58 22 



36 



THE WINDMILL AS A PRIME MOVER. 



The diagram * (Fig. 3) shows graphically the best an- 
gles of impulse and of " weather," as determined above. 
The ordinates represent the best angles of weather and 
impulse, expressed in degrees ; and the abscissas, the ratio 




OJ 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 14 1.1 1.2 1.3 1.4 1 .5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3^ 3.3 3.4 3^ 

Fig. 3. 



of the velocity of the wind to the velocity of the wind- 
mill blades, -. Thus, assuming the velocity of the wind 
to be 31.416 feet per second, the diameter of the wheel to 
be 35 feet, and the number of revolutions per minute 
to be made to equal 30, the velocity of the wind wheel at 



* Originally presented by the author in the Engineering and Mining Journal 
Oct. 26, 1878. See also Appleton's Cyclopaedia of Mechanics, 1880; Transactions 
American Society Mechanical Engineers, 1882; American Engineer, April 22, 1882; 
Journal of the Franklin Institute, July, 1882; Engineering, Aug. 18, 1882; Proceed- 
ings Institution Civil Engineers, vol. lxx., session 1881-82, Part IV. 



THE IMPULSE OF WIND ON WINDMILL BLADES. 37 

a point 2.5 feet from the centre of the shaft will be 7.854 
feet per second ; at 5 feet from the centre, 15.708 ; at 7.5 
feet, 23.562; etc.: and the ratio of the velocity of the 
wind to the velocity of the sail, -, will at 2 5 feet from 
centre of shaft equal 0.25 ; at 5 feet, 0.50; at 7.5 feet, 
0.75 ; etc. The best angle of weather equals, therefore, 
at a distance 2.5 feet from the centre of the shaft, 3 8° ; 
at 5 feet from the centre, 32 ; at 7.5 feet, 27 ; etc. : and 
the best angle of impulse equals, at a distance of 2.5 
feet from the centre of the shaft, 52 ; at 5 feet from the 
centre, 5 8° ; at 7.5 feet, 63 ; etc. 

Since there is no difference in the amount of effect 
caused by the blades moving against the air, and that 
caused by the air (or wind) striking upon the blades 
(assuming the same velocity in both cases) , the angles 
set forth in the table and diagram will be found to be 
those of maximum efficiency for ventilating purposes as 
well as for windmills. 

Theoretical Mechanical Effect of Windmill of Shape 
of Sail for Maximum Effect. 

Having given the velocity of the wind and the number 
of revolutions and the dimensions of the sail, the shape of 
the surface producing the maximum effect, and the cor- 
responding theoretical effect, can be readily found. 

Let c = velocity of the wind, in feet per second ; 

n = number of revolutions of the windmill per minute ; 
K> bv h, • ' ' &*> be the breadth of the sail at distances 4, /„ 4» 
/ 3 , . . . /, respectively, from the axis of the shaft ; 



38 THE WINDMILL AS A PRIME MOVER. 

Let 4 = distance from axis of the shaft to the beginning of sail proper ; 
/ = distance from axis of the shaft to the extremity of sail proper ; 
Vo, v u v 2 , z> 3 , . . . v x , be the velocity of the sail, in feet per second, 

at distances 4, 4, 4, / 3 , • • • 4 respectively, from the axis 

of the shaft ; 
<*<>, <*i, <*2, « 3 , . . . a x > be the angles of impulse for maximum effect 

at distances 4, /„ 4, 4, • • • 4 respectively, from the axis of 

the shaft. 

Then will 

v = 0.104724**, 

Vi = 0.10472/,*, 
v 2 = 0.104724*, 

V x =z O.IO472/*; 

and, from (III.), 

0.104724* * / /o. 104724* V 
tan« T— + V I + (, ; )> 



0.104724 
tana, = 



'* + y/x + ^"H7^ 



0.10472/* 
tan 0* = + 



y/x + (2i212^J. 



From these equations can be found the angle which 
the direction of the wind must make with the sail at 
any point on its surface, in order to give the best effect. 
As the shaft of a vertical windmill is parallel to the 
direction of motion of the wind, these angles represent 
also those which the elements of the surface at distances 
4» / x , / a i • • • A make respectively with the axis of the shaft ; 
or, the elements of the sail must make the complements 



.AE IMPULSE OF WIND ON WINDMILL BLADES. 39 

of these angles (angles of weather) with the plane of 
motion of the sail. Having, therefore, found the Angles 
of impulse, as indicated above, the shape of sail for 
maximum effect is determined. The theoretical effect 
for this sail is computed by application of formula (I.), 



SK*d 

Lv = 

g 

From (II.) we have 



7- v V 
^4 sin a cos a lcosi 



c\an 2 a — i c , 

v = ss -(tana — cot a). 

2 tana 2 V ' 

Substituting this value of v in (I.), 

SKdc* , / tana — cota \ 
Lv = (tana — cota)f sin a cosa Jcosa, 

SKdfil 
Lv = ( tan a sin a cos a — cot a sin a cos a 

tan a (tan a — cot a) cos 2 a cot a (tan a — cot a) cos* a\ 
- + - J, 

SKd&l . tan 2 a cos 2 a 
Zp = 1 sin 2 a — cos 2 a 

2g \ 2 

tan a cot a cos 2 a cot ataxia cos 2 a cot 2 a cos a a\ 

+ 2 + i i ) 

SKd&t . sin 2 a cos 2 a cos 2 a cos 4 a \ 
Lv = 1 sin 2 a — cos 2 a 1 h r-r~ J, 

2^ \ 2 2 2 2 Sin 2 0/ 



__ SKdc* (sin 2 a cos 4 a \ __ SKdc*fsm<a — cos 4 a\ 
"" - -- 2 sin 2 ay "" 4^ \ sin 2 a / 



SKdc*((sm 2 a + cos 2 a) (sin 2 a — cos 2 a)> 
Lv = 



4? 



3 /(sin 2 a 4- cos 2 a) (sin 2 a — cos 2 a)\ 
\ sin 2 a ) 



SKdc*(ism*a — i\ 
4g \ sin 2 a / 



40 THE WINDMILL AS A PRIME MOVER. 

S = (/ - l )B (B = mean breadth of sail), 



and 



(/ - I ) Kdc* 2 sin 2 a — i 
Lv = B- 



4g sin 2 a 

B(2 sin 2 a -*■ i) 



sura 



= the mean of 



/2sm 2 a — i 2 51^^, — i 2 sin 2 a* — i z \ 

\ sin 2 a *» sin 2 a, * w * ' ' sin 2 ^ b *} 

Therefore the theoretical mechanical effect of the 
windmill of shape of sail for maximum effect (when 
N = number of sails or blades of windmill) equals 



N 1 X mean of 

Ag 

2 sin 2 a Q — i . 2 sin 2 a x — i , 2 sin 2 a x — 1 

— — % K — — % 4>, . . . ^f b„ (IV.) 

sin 2 a ' sin 2 a x ' sm 2 a x x v ' 



Theoretical Mechanical Effect of Windmill with Plane 

Sails. 

If the sail is a plane, the angle of impulse a will be 
a constant quantity; and hence we find from (I.), for 
the theoretical mechanical effect of a windmill with plane 
sails, the value 



g 



(l-l )k<*dN r /. v \ 

- X mean of I v Q (sin a cos a w cos a 

• • • v x [ sin a cos a\b x cos a . (V.) 



THE IMPULSE OF WIND ON WINDMILL BLADES. 4 1 

Loss of Effect by Friction of the Shaft. 

In calculating the amount of friction, the whole weight 
of the wheel is taken as bearing upon the neck gudgeon, 
and the pressure upon the lower bearing is not consid- 
ered. This certainly seems, at first sight, like finding an 
excess of friction, part of the weight evidently resting 
upon the lower bearing; but it must be remembered, 
first, that this excess is compensated by the fact that no 
attention is paid to the axial component of the pressure 
of the wind, and, secondly, by the fact of the considerably 
greater diameter of the upper than of the lower bearing. 

Let W = weight of wind wheel in pounds, 

/* = co-efficient of friction of shaft and bearings, 
n = number of revolutions of the windmill per minute, 
D = diameter of upper bearing in feet. 

The work expended in overcoming the friction will 
equal the amount of friction into the velocity with 
which it is overcome. This velocity in feet per second 
= 0.05 236/zZ?, and the loss of effect by friction =ffV 
X 0.05 236^/?, which, subtracted from (IV.), makes 

The actual mechanical effect of a windmill, with sails of best angles of 
weather, equal to 



(/ — Qkdc* „ 1 2 sin 2 a Q — 1 , 
5 X mean of V sin-* '• 

• • * "^J"' **) S W * 0.05236*/). (VI.) 
* For the coefficient of friction in shafts, see chap, x., p. 150. 



42 THE WINDMILL AS A PRIME MOVER. 

Subtracting the loss of effect by friction of the shaft 
from (V.), we have, for the actual mechanical effect of a 
windmill with plane sails, the value 



X mean of v Q (sin a cos a) b Q cos a 



(I-I )kc*dN 
g 

. . . v x ( sin a — ~ cosaj6 x cosa \—flVx 0.0523691!?. (VI.) 

Proof of Accuracy of Formula {IV.). 

It is always well to put a formula, however evident it 
may appear theoretically, to a practical test, to ascertain 
its truth. The only practical test which can be applied in 
this case is a comparison of the effect produced, given as 
the result of Coulombs* experiments, and the effect as 
deduced from the formulae. Coulomb found as the total 
effect, including friction of the shaft, 1 ,000 pounds raised 
2 53 fads de rot = 269.6 English feet for a windmill of 
the following dimensions and given conditions : Length 
of sail = /= 33 French feet = 35.171 English feet ; dis- 
tance from axis of shaft to beginning of sail = l Q = 6 
French feet = 6.395 English feet ; breadth of sail = 
about 6.2 French feet = 6.6195 English feet; number of 
revolutions per minute = n = 13 ; number of sails = N 
= 4 ; velocity of wind = about 20.5 French feet per 
second = 21.982 (or about 22) English feet per second ; 
angle of impulse at 4 = nearly 6o°, angle at / = 78 . 
The intermediate angles are not given ; but, judging by 

* See p. 128. 



THE IMPULSE OF WIND ON WINDMILL BLADES. 43 

the agreement of the angles of impulse at 4 and l lf the 
windmill can be considered as having sails very nearly 
of shape for maximum effect. 

Let / = 6.395 ft. Then v = 8.70590 ft. per sec, tan Oo = 1 48861, .\ a = 56 6'30 lr . 

l x = 1 1. 17 1 " " vi = 15.23498 " tanfl t = 1.94388, .\a t = 62°46'38 # . 

4 = 15987 " " v 2 = 21.76406 " tana 2 = 2.45017, .\a 2 = 67°45'26 lr . 

/ 3 = 20.783 " " v 3 = 28.29314 " tan # 3 = 3.00713, .\a z = 7i°3&20*. 

U = 25.579 " " ^4 = 34-82222 " tan « 4 = 3.5490^ •*• *4 = 74°i5'5 0# - 

4 = 3°-375 " " ^s = 4i-35 I 3° " tan "s = 4-12235, ;.a 5 = 76°2i'54*. 

/ =35 r 7i " "^=47.88038 " tan a x = 4.70488, :.a x - 78° o 7 2'. 

(2sin»56°6'3o'-i) ^^ (2 sin»7i° 3^0' - 1) r ^ 

sin 2 56° 6'3o" *^ sin 2 71° 36^0^ ** * ,. 

(2 sin* 62046*38" -1) (2sin 2 74 o T5 / 5O ff -0 - 1?0? ^ > 

sin* 62° 4 6'38" ~~ ' /4/ * sin 2 74 1 5*50" - v «** 

(2sin 2 6 7 45 , 26^i) _ g (2sin* 7 6 21*54' - 1) = 

sin 2 6 7 °45'26' f -°°3 Z7 > sin 2 76 21*54' * * 

(2sm 2 7 80o'2'-i) ~ 

sin 2 78° o' 2 " y!)4 J 

the mean value of which, according to Simpson's rule, = 
0.84458. Substituting the above values in equation (IV.), 

4 x 6.6195 x 28.776 0.93 x dc 2 n 

Lv = — — x -^ X 22 X 0.84458 ; 

4 g 

and assuming the average temperature at time of obser- 
vation = 50 F., and the barometric pressure = 2088.5 
(at 32 F. this = 21 16.5), — = 1.2, and Lv = 6.6195 X 
28.776 X 0.93 X 1.2 X 22 X 0.84458 = 3949.9 foot-pounds 
per second = 236,994 foot-pounds per minute = 1,000 
pounds raised 236.994 feet per minute. It will be noticed 
that the effect as here calculated from the formula is 

* These angles can be obtained directly from diagram, Fig. 3, or Table V., 
without first finding value of tan a, as has here been done as a mere matter of 
interest. 



44 THE WINDMILL AS A PRIME MOVER. 

smaller than the actual effect ; while, on account of the 
better angles of impulse, it should be somewhat larger. 
But, if the barometric pressure had equalled 2349.81 
(at 32 this = 2381.06), then — = 1.35, and Lv = 
6.6195 X 28.776 X 0.93 X 1. 35 X 0.84458 X 60 = 266,618 
foot-pounds per minute = 1,000 pounds raised 266.618 
feet per minute ; or, if instead of c = 22 English feet, the 
velocity had been 23 English feet per second, — x c = 
iworio ?7?I X 23 = 30.36 (the barometric pressure 

_59°3; 0.018743 

529 

being assumed = 2088.5), Lv = 6.6195 x 28.776 X 0.93 
X 30.36 X 0.84458 •= 4541.4 foot-pounds per second = 
1,000 foot-pounds raised 272.486 English feet per minute, 
which is slightly above the effect found by experiment. 
Now, the barometric pressure at the time of the obser- 
vations might have been 2381.6 pounds per square foot, 
instead of 2088.5, no record of the same having been 
kept. Also, judging from the method by which the ve- 
locity of the wind was ascertained,* an error of one foot 
per second was very easily possible ; and it is even prob- 
able that the velocity of wind found differed somewhat 
from the velocity with which the wind struck the mill, 
no anemometer having been employed. However, the 
close approximation between the results as determined by 
calculation and by experiment is immediately discernible, 
and various formulae extant tested by the writer in the 
same manner failed to give nearly as satisfactory results* 

* See p. 130. 



THE EARLY HISTORY OF WINDMILLS. 4*5 



CHAPTER III. 

THE EARLY HISTORY OF WINDMILLS. 

All of paramount interest pertaining to the early- 
history of windmills has been collated by Professor John 
Beckmann in his " History of Inventions and Discover- 
ies." The work of this distinguished ".public professor 
of economy in the University of Gottingen " has, as we 
have found by careful search, been exhaustive ; and it is 
a pleasure, therefore, to acknowledge our indebtedness 
to this valuable treatise, or more directly to the transla- 
tion by Mr. William Johnston, London, 1817, for all the 
facts detailed in this chapter. 

§ In vol. i., under the heading " Corn Mills," p. 247, 
we read, — 

" The intrusting of that violent element water to support and drive 
mills constructed with great art, displayed no little share of boldness ; 
but it was still more adventurous to employ the no less violent but 
much more untractable and always changeable wind for the same pur- 
pose. Though the strength and direction of the wind cannot be any 
way altered, it has, however, been found possible to devise means by 
which a building can be moved in such a manner that it shall be 
exposed to neither more nor less wind than is necessary, let it come 
from what quarter it may. 

" It is very improbable — or, much rather, false — that the Romans 



46 THE WINDMILL AS A PRIME MOVER. 

had windmills ; though Pomponius Sabinus affirms so, but without any 
proof.* Vitruvius,t where he speaks of all forces, mentions also the wind • 
but he does not say a word of windmills. Nor are~they noticed erther 
by Seneca X or Chrysostom,§ who have both spoken of the advantages of 
the wind. I consider as false also the account given by an old Bohe- 
mian annalist, || who says that before the year 718 there were none but 
windmills in Bohemia, and that water-mills were then introduced for the 
first time. I am of the opinion that the author meant to have written 
hand and cattle mills instead of windmills. 

" It has been often asserted that " these mills were first invented in 
the East, arid introduced into Europe by the Crusaders ; but this also is 
improbable, for mills of this kind are not at all, or very seldom, found 
in the East. There are none of them in Persia, Palestine, or Arabia ; and 
even water-mills are there uncommon, and constructed on a small scale. 

" Besides, we find windmills before the Crusades, or at least at the 
time when they were first undertaken. It is probable that these 
buildings may have been made known to a great part of Europe, and 
particularly in France and England,^ by those who returned from these 
expeditions ; but it does not thence follow that they were invented in 
the East.** 



* See Pomponius Sabinus, ut supra. j 

t Lib. ix. c. 9, lib. xc. 1, 13. 

% Natur. Quaest., lib. v. c. 18. 

§ Chrysost. in psalm cxxxiv. p. 362. 

|| " At the same period [718], one named Halek, the son of Uladi the Weak, 
built close to the city an ingenious mill which was driven by water. It was visited 
by many Bohemians, in whom it excited much wonder, and who, taking it as a model, 
built others of the like kind here and there on the rivers ; for before that time all 
the Bohemians' mills were windmills erected on mountains." 

1" See De la Mare, Traite* de la Police, etc., ut supra ; Description du Duche 
de Burgogne, Dijon, 1775, 8vo, i. p. 163; Dictionnaire des Origines, par D'Origny, 
v. p. 184. The last work has an attractive title ; but it is the worst of its kind, 
written without correctness or judgment, and without giving authorities. 

** " There are no windmills at Ispahan nor in any part of Persia. The mills 
are all driven by water, by the hand, or by cattle*' (Voyages de Char din, Rouen, 



THE EARLY HISTORY OF WINDMILLS. 47 

"The Crusaders perhaps saw such mills in the course of their 
travels through Europe ; very probably in Germany, which is the original 
country of most large machines. In like manner, the knowledge of 
several useful things has been introduced into Germany by soldiers who 
have returned from different wars ; as the English and French, after their 
return from the last war, made known in their respective countries many 
of our useful implements of husbandry, such as our straw-chopper, 
scythe, etc. 

"Mabillon mentions a diploma of the year 1 105, in which a con- 
vent in France is allowed to erect water and wind mills, molendina ad 
ventum* In the year 1143, there was in Northamptonshire an abbey, 
situated in a wood, which in the course of a hundred and eighty 
years was entirely destroyed. One cause of the destruction was said 
to be, that in the whole neighborhood there was no house, wind or 
water mill built, for which timber was not taken from this wood.f 

1723, 8vo, viii. p. 221). "The Arabs have no windmills: these are used in the East, 
only in places where no streams are to be found. And in most parts the people 
make use of hand-mills. Those which I saw on Mount Lebanon and Mount 
Carmel had a great resemblance to those which are found in many parts of Italy. 
They are exceedingly simple, and cost very little. The millstone and the wheel are 
fastened to the same axis. The wheel, if it can be so called, consists of eight 
hollow boards, shaped like a shovel, placed across the axis. When the water falls 
with violence upon these boards, it turns them round, and puts in motion the mill- 
stone, over which the corn is poured " (D'Arvieux : Merkwurdigt Nachrichtcn 
von seinen Reisen y Part III., Copenhagen and Leipsic, 1754, 8vo, p. 201). "I did 
not see either water or wind mill in all Arabia. I, however, found an oil-press at 
Tehama, which was driven by oxen, and thence suppose that the Arabs have corn- 
mills of the like kind" (Niebuhr: Beschreibungvon Arabten, p. 217). 

* " Iisdem etiam facultatem concessit constituendi domos, stagna, molendina 
ad aquam et ventum, in episcopatu Ebroicensi, Constantiensi, et Bajocensi, ad 
augendos monasterii proventus " (Mabillon: Annates Ordanis S. Benedicti, 
torn, v., Lut, Paris, 17 13, fol. p. 474). 

t " Praeterea non fuit in patria, aula, camera, orreum, molendinum venticium 
sive aquaticum alicujus valoris plantata sine adminiculo aliquo boscorum Sanctae 
Mariae de Pipewalla [so the wood was called] quot virgas molendinorum venticio- 
rum dabauntur in temporibus di versorum abbatum nemo novit, nisi Deus. Caussa 



48 THE WINDMILL AS A PRIME MOVER. 

" In the twelfth century, when these mills began to be more common, 
a dispute arose whether the tithes of them belonged to the clergy ; and 
Pope Celestine III. determined the question in favor of the Church.* 
In the year 1332 one Bartolommeo Verde proposed to the Venetians to 
build a windmill* When his plan had been examined, a piece of ground 
was assigned to him, which he was to retain in case his undertaking 
should succeed within a time specified.t In the year 1393 the city of 
Spires caused a windmill to be erected, and sent to the Netherlands for 
a person acquainted with the method of grinding by it.J 

" A windmill was also constructed at Frankfort in 1442, but I do not 
know whether there had not been some there before.§ 

" To turn the mill to the wind, two methods have been invented. 
The whole building is constructed in such a manner as to turn on a post 
below, or the roof alone, together with the axle-tree ; and the wings are 
movable. Mills of the former kind are called German mills ; those of 
the latter, Dutch. They are both moved round, either by a wheel and 
pinion within, or by a long lever without. || I am inclined to believe 
that the German mills are older than the Dutch ; for the earliest descrip- 



tertia destructionis boscorum fruit in constructione et emendatione domorum infra 
abbathiam et extra utpote grangus, orreis, bercariis molendinis aquaticis et venticiis 
per vices. [The letter of donation, which appears also to be twelfth century, may 
be found in the same collection, vol. ii., p. 459. In it occurs the expression, 
molendinum ventritricum. In a character, also, in vol. iii., p. 107, we read of mo- 
lendinum ventoriurn] " (Monasticon Anglicanum sive Pandicte C<znobiorum> edit, 
sec. London, 1682, fol. i. p. 816). 

* De reditibus molendini ad ventum solvendae sunt decimse, Decretal Greg., 
lib. iii. tit. 30, c. 23. 

t Gir. Zanetti, Dell' Origine di alcune arte appresso di Veneziani, Venez., 
1758, 4to, p. 74; Pro faciendo unum molendinum a vento; Le Bret, Geschichte 
von Venedig, II. i. p. 233. 

% Lehmann's Chronica der Stadt Speyger, Frankf., 1662, 4to, p. 847 : " Sent 
to the Netherlands for a miller who could grind with the windmill." 

§ Lersner, Frankf. Chronik, ii. p. 22. 

|| Description and figures of both kinds may be found in LeupokTs Theatrum 
Machinarum Generale, Leipsic, 1724, fol. p. 101, tab. 41-43. 



THE EARLY HISTORY OF WINDMILLS. 49 

tions which I can remember, speak only of the former. Cardan,* in 
whose times windmills were very common, both in France and Italy, 
makes, however, no mention of the latter ; and the Dutch themselves 
affirm, that the mode of building with a movable roof was first found out 
by a Fleming in the middle of the sixteenth century .f 

"Those mills by which, in Holland, the water is drawn up and 
thrown off from the land, one of which was built at Alkmaar in 1408, 
another at Schoonhoven in 1450, and a third in Enkhuysen in 1452, 
were at first driven by horses, and afterwards by wind. But as these 
mills were immovable, and could work only when the wind was in one 
quarter, they were afterwards placed, not on the ground, but on a float 
which could be moved round in such a manner that the mill should 
catch every wind.{ This method gave rise, perhaps, to the invention of 
movable mills." 

An interesting episode relative to the use of wind- 

* " Nor can I pass over in silence what is so wonderful, that, before I saw it, I 
could neither believe nor relate it, though commonly talked of, without incurring 
the imputation of credulity. But a thirst for science overcomes bashfulness. In 
many parts of Italy, therefore, and here and there in France, there are mills which 
are turned round by the wind " {De Rerum Varietate, lib. i. cap. 10, in the edition of 
all his works, Lugduni, 1663, fol. vol. iii. p. 26). 

t This account I found in De koophandel van Amsterdam, door Le Long, 
Amsterdam, 1727, 2 vols. 8vo, n, p. 584: " De beweegelyke kap y om de moolens op all 
windens te zettens, is erst in't midden van de xvide eeuw door een Vlaaming uytge- 
vonden " (" The movable top for turning the mill round to every wind was first 
found in the middle of the sixteenth century by a Fleming "). We read there that 
this is remarked by John Adrian Leegwater ; but of this man I know nothing more 
than what is related of him in the above work, that he was celebrated on account 
of various inventions, and died in 1650, in the seventy-fifth year of his age. See 
also Beschryving der Stadt Delft door verscheide Liefhebbers en Kenners der 
Nederlandsche oudhedin. Te Delft, 1729, fol. p. 623. 

% "De molens hadden doen (toen) vaste kappen zoo datze maarmet eenewind 
malen konde, waarom men op zekere plaats, om dit ongeval voor te kommen, een 
molen op een groot vlot neder zette dat men dan naar din wind draide." See the 
History of the city of Delft, above quoted. 



50 THE WINDMILL AS A PRIME MOVER. 

mills, of special interest to the school of political econo- 
mists, who hold that any of the free forces of nature, 
such as air, water, land, and the like, should, in their 
natural, unimproved offering, be the equal property of 
all, is noted by Beckmann, on p. 268, as follows : — 

" The avarice of landholders, favored by the meanness and injustice 
of governments, and by the weakness of the people, extended this 
regality not only over all streams, but over the air and the windmills. 
The oldest example of this with which I am at present acquainted is 
related by Jargow.* 

"In the end of the fourteenth century, the monks of the celebrated 
but long since destroyed monastery of Augustines at Windsheim, in 
the province of Overyssel, were desirous of erecting a windmill not far 
from Zwoll; but a neighboring lord endeavored to prevent them, de- 
claring that the wind in the district belonged to him. 

" The monks, unwilling to give up their point, had recourse to the 
Bishop of Utrecht, under whose jurisdiction the province had continued 
since the tenth century. The bishop, highly incensed against the pre- 
tender who wished to usurp his authority, affirmed that the wind of the 
whole province belonged to him only, and in 1391 gave the convent 
express permission to build a windmill wherever they thought proper, f 

* Jargow, Einleitung in die Lehre von den Regalien, Rostock, 1757, 4to, p. 494. 

t " As our monastery had not a mill to grind corn, they resolved to build a new 
one. When the lord of Woerst heard this, he did every thing in his power to 
prevent it, saying that the wind in Zealand belonged to him, and no one ought to 
build a mill there without his consent. The matter was therefore referred to the 
Bishop of Utrecht, who, as soon as the affair was made known to him, replied in a 
violent passion that no one had power over the wind within his diocese but himself 
and the church at Utrecht; and he immediately granted full power, by letters- 
patent, dated 1391, to the convent at Windsheim, to build for themselves and their 
successors a good windmill in any place which they might find convenient" 
[Chronicon Canonicorutn regularium ordinis Augustini, capituli Windesemensis t 
auctore Joh. Buschio y Antverpiae, 162 1, 8vo, p. 73). 



THE EARLY HISTORY OF WINDMILLS. 5 1 

" In like manner, the city of Haerlem obtained leave from Albert, 
count palatine of the Rhine, to build a windmill, in the year 1394."* 

* " Albertus notum facimus quod donavimus donamusque civitati nostrae 
Harlemianae ventum molarium a parte australi civitatis nostrae praiscriptae hemi- 
stadium versus inter Pacis fossam et sparnam." (Theod. Schrevelii : Harlemum 
Lugduni, Batavorum, 1647, 4 t0 > P* 181). 



THE WINDMILL AS A PRIME MOVER. 



CHAPTER IV. 

EUROPEAN WINDMILLS. 

European windmills have been divided into two gen- 
eral classes, according to the inclination of the shaft : — 

1. Horizontal Mills, in which the sails were so 
placed as to turn, by the impulse of the wind, in a hori- 
zontal plane, and hence about an axis exactly vertical ; 
and 

2. Vertical Mills, in which the sails turn in a nearly 
vertical plane, i.e., about an axis nearly horizontal. 

Horizontal Mills, 

On account of the many disadvantages connected 
with the horizontal mills, their use has been exceedingly 
limited. They have been employed only in situations 
in which the height of the vertical sails proved a serious 
objection, — a rare and extraordinary occurrence. This 
class of mill demands, therefore, but little notice on our 
part. Its general construction may be outlined to this 
effect : Six or more sails, consisting of plane boards, are 
set upright upon horizontal arms which rest upon a tower, 
and which are attached to a vertical shaft passing through 



EUROPEAN WINDMILLS. 53 

the centre of the tower. The sails, which are fixed in 
position, are set obliquely to the direction in which the 
wind will strike them. Outside of the whole is placed a 
screen or cylindrical arrangement of board intended to 
revolve, these boards being set obliquely, and in planes 
lying in opposite course to those of the sails. As a 
result, from whatever direction the wind may blow against 
the tower, it is always admitted by the outer boards to 
act on the sails most freely in that half of the side it 
strikes on, from which the sails are turning away; and 
it is partly, though by no means entirely, broken from the 
sails which, in the other quadrant of the side, are ap- 
proaching the middle line. Fairbairn* reprints from the 
columns of the " Practical Mechanic's Magazine " the fol- 
lowing account of a horizontal windmill at Eupatoria in 
Crimea, as it appeared when seen by the writer of the 
article during the period of the Crimean War. This 
description will well answer for the whole type. It 
reads : — 

" Around the town of Eupatoria, in the Crimea, there appeared to 
be nearly two hundred windmills, chiefly employed in grinding corn ; 
and all which were in a workable state were of the vertical construction, 
and only one horizontal mill, which seemed to have been out of use 
for at least a quarter of a century. The tower of this mill was built of 
brickwork, about twenty feet diameter at the base, and about seventeen 
feet at the top, and twenty feet high. The revolving wings, which con- 
sisted of six sets of arms, appeared to be about twenty feet diameter 
and about six feet broad, fitted with vertical shutters which were 

* Treatise on Mills and Millwork, by Sir William Fairbairn. 



54 THE WINDMILL AS A PRIME MOVE 

movable on pivots passing through the arms, the shutters being about 
twelve inches wide by five or six feet high ; and the pivots were fixed 
at about one-third of the breadth from the edge of the shutters, in 
order that the wind might open and shut them at the proper time 
during the revolution of the wings. About one-third of the circum- 
ference of the wings was surrounded by a segmental screen, to shelter 
the arms and shutters while moving up against the wind ; and the screen 
seemed to have been hauled round with ropes, in order to suit the 
direction of the wind." 

The objections to the employment of the horizontal 
windmill, which virtually debarred, and still debar it from 
use in competition with the vertical mill, are, first, that 
only one or two sails can be effectually acted upon at the 
same moment ; and secondly, that the sails move in a 
medium of nearly the same density as that by which they 
are impelled, and that therefore great resistance is 
offered to those sails which approach the middle. 
Smeaton* puts it thus : — 

" Little more than one sail can be acting at once, whereas in the 
common windmill all the four act together; and therefore, supposing 
each vane of a horizontal windmill of the same dimensions as each 
vane of the vertical, i* is manifest that the power of a vertical mill with 
four sails will be four times greater than the power of the horizontal 
one, let its number of vanes be what it will. This disadvantage arises 
from the nature of things ; but, if we consider the further disadvantage 
that arises from the difficulty of getting the sails back against the wind, 
etc., we need not wonder if this kind of mill is in reality found to have 
not above one-eighth to one-tenth of the power of the common sort, 
as has appeared in some attempts of this kind." 

* Philosophical Transactions, 1755 to 1763. 



EUROPEAN WINDMILLS. 55 

While it is true, that, with a like area of sails, the 
power of the horizontal is always much less than that of 
the vertical mill, Smeaton's estimate of one to eight or 
one to ten is too unfavorable, inasmuch as he overlooked, 
as Sir David Brewster first showed, the loss in vertical 
mills of one component of the wind's pressure.* The 
ratio of one to four, given by Sir David Brewster, is, 
however, about the correct figure, and presents a suf- 
ficient explanation of the limited use to which horizontal 
windmills have been put in the past, and a sufficient 
cause why they should not be employed at the present 
time, if the question of economy of motive power at all 
enters the problem as a leading consideration. 

Vertical Mills. 

In vertical mills of the European type, the tower or 
building which supported the windmill proper was either 
of wood or stone : if of stone, the tower was commonly 
in the form of a frustum of a cone. The principal parts 
of the mill proper are : — 

i. An axle or shaft, either of wood or iron, in the top 
of the building, inclined to the horizontal at an angle of 
from ten to fifteen degrees, as observation has shown 
that the impulse of the wind is usually exerted in lines 
descending at such angles. 

2. The sails, attached to near the outer extremity of 
the shaft, and turning in nearly a vertical plane. The 

* See p. 30. 



56 THE WINDMILL AS A PRIME MOVER. 

planes of these sails are placed obliquely to the plane of 
revolution ; so that, when the wind blows in the direction 
of the axle, it impinges upon their surface obliquely, and 
thus the effort of the sail to recede from the wind causes 
it to turn upon its axle. These sails consist of wooden 
frames (arms and cross-bars) , with canvas covering the 
lattice or frame work. If four in number, as is the rule, 
though five and six have been employed, the sails are 
fixed in position at right angles to each other. They are 
usually constructed from thirty to forty feet in length, 
though fifty feet has often been exceeded. 

3. A large toothed wheel upon the horizontal axle, 
the teeth of which engage with those of a pinion 
upon 

4. A vertical shaft from which motion is imparted to 
the machinery. 

It will be understood that the horizontal shaft is 
supported at its inner end near the centre of the base of 
the dome or cone surmounting the mill, while its opposite 
extremity passes through a perforation in one side of the 
dome, where it has its main support, and projects far 
enough to receive the ends of the long timbers or arms 
of the sail. The pivot at the lower or inner end of the 
shaft takes up but a small part of the weight and counter- 
pressure. 

The axle is constructed of some hard wood, like oak, 
or of wrought-iron with cast-iron flanges of large diam- 
eter keyed on the front, which are furnished with re- 
cesses for receiving and holding the arms of the sails. 



EUROPEAN WINDMILLS. 



57 



Windmill Sai&r 




R 



=* 



'R- - 



x 



Fig. 4. 



58 THE WINDMILL AS A PRIME MOVER. 

The latter must be proclaimed as the better practice; 
since, the diameter of the neck of the wooden shaft being 
from one and a half to two feet, an iron one substituted 
in its place need not be more than six to nine inches, 
and thus the loss by friction * is materially decreased. 

The sails are made plane, concave, or warped. The 
latter, the most effective, have been in greatest use ; 
and the angles employed in the Dutch type of millf 
have, on the whole, approached very closely to those 
which theoretical analysis proves to be most serviceable. 
Where plane sails have been used, the bars have all had 
the same angle of inclination, ranging between twelve 
and eighteen degrees to the plane of revolution. 

Reference to Fig. 4, taken in connection with the 
description of. the windmills experimented upon by 
Coulomb, X as we H 2^ the accounts and illustrations of 
special types given in this chapter, will not render it 
necessary to say more in a general way about the sails, 
than that they are either of rectangular or (more usually) 
of trapezoidal form, increasing in width as they approach 
the outer extremity of arm ; that the innermost cross-bar 
is placed at about one-sixth to one-seventh of the length 
of the arm from the middle of the shaft; and that its 
length is about equal to this distance. So the canvas 
lattice-work covers only five-sixths or six-sevenths of the 
outer portion of the sails. In a sail about thirty feet long, 
the arms near the shaft are about one foot thick and nine 

* See p. 41. t See p. 42. 

t See p. 128. 



EUROPEAN WINDMILLS. 



59 




Fig. 5. 



60 THE WINDMILL AS A PRiMK MOVER. 

inches wide, and at the outer end about six inches thick 
and four and a half inches wide. 

As the direction of the wind is changing perpetually, 
some contrivance is necessary for bringing the shaft into 
the direction of the wind, so that the sails will be acted 
upon most effectively. According as this revolution is 
effected, European vertical windmills have been divided 
into two general types : — 

i. The Post or German Mill, in which the whole 
building which sustains the wind sails, shaft, and the 
machinery is supported upon a vertical post or column, 
upon which it revolves at will when actuated by a lever. 

2. The Tower or Dutch Mill, in which only the 
head, cap, or dome of the building, with the shaft which 
it contains, revolves. 

Post or German Mills. 

It will be readily understood that not only are these 
mills necessarily limited in their size, but the manual 
labor their turning to the wind implies, led to their 
effectual abandonment when the tower mills had been 
made automatic in their regulation. 

Fig. 5 shows a general view of a post mill, for which 
we are indebted to "A Manual of the Mechanics of En- 
gineering and of the Construction of Machines," by Dr. 
Julius Weisbach, voL ii., translation of Professor A. J. 
Du Bois, 1880, p. 637, 

AA is the upright standard, supported by the cross- 



EUROPEAN WINDMILLS. 6 1 

timbers BB and B X B X > and by the braces C and D\ all 
these parts constituting the so-called post. On the head 
of the post is firmly placed the saddle E, composed of 
four pieces of wood fastened together. The mill house 
is supported by the two cross-beams, FF, an$ by two of 
the six cross-lying floor timbers, GG. It rests also upon 
the strong cross-timber H y which turns, by means of a 
pivot, upon the head of the post. The neck N of the 
axle KL turns in a metal or stone (basalt) plumber 
block, which rests upon the strong axle timber MM, 
the latter being supported by the roof framework 00. 

Fig. 6 gives a sectional view of a post mill, taken 
from the " Encyclopaedia of Arts, Manufactures, and 
Machinery," by Peter Barlow, F.R.S., professor at the 
Royal Military Academy , Woolwich ; London, 1851. We 
copy the following description of this mill, verbatim, from 
the same source : — 

"AB is the wind shaft, one end of which has a bearing on the beam 
C of the framing of the mill, and the other is supported in a similar way 
by a beam D ; the part of the shaft outside the mill is larger, and made 
square, and has two square holes or mortises through it, into which the 
whips or arms of the sails are fitted, and made fast by wedges, aa. 
The wheel EE, which is termed the brake wheel, is attached to the 
wind shaft; it has a rim of wood, bb, on its circumference, termed 
the brake, one end of which is attached to a fixed part of the mill, and 
the other by means of an iron rod, to a lever, cd\ so that, by pressing 
down the end of the lever, the brake is made to bind upon the cir- 
cumference of the wheel, and thereby produces such a resistance that 
the mill may be at any time stopped. The brake wheel is here 
represented on the old construction; i.e., the face wheel, which is 
supposed to work a trundle not shown in the figure. 



62 



THE WINDMILL AS A PRIME MOVER. 



" The lower floor of the mill is made to receive the post P> upon 
which the mill is turned round to face the wind. This post is a very 
strong tree, which is held perpendicularly by fixing it upon the middle 



Post Mill. 




Fig. 6. 



of two long timbers, which form a large cross upon the ground, and 
which constitute the base of the whole mill. The post is secured in its 
vertical position by four oblique braces, F, F, F, F, which extend from the 
ground cross to the middle of it ; leaving ten or twelve feet of the upper 
part, which is made round, clear from the obstruction of the braces. 



EUROPEAN WINDMILLS. 63 

This round part of the post rises up through the middle of the lower 
chamber, in the floor of which a circular collar is formed to the exact 
diameter of the post. At the upper end of the post is a pivot or 
gudgeon, which enters into a socket fixed to one of the strongest 
beams, G, in the middle of the upper floor ; this beam must necessarily 
be very strong, as it has to sustain the whole weight of the erection. 
In this way the mill is made to turn freely upon the pivot, while the 
collet in the lower floor serves to keep it steady and in a vertical 
position. L is a ladder for the purpose of ascending to the mill : it is 
united by joints to the back part of the framing, and has a rope, M 9 
fastened to the lower end, which passes in an inclined direction into 
the mill, so that, by a lever or pulleys, it can be raised at pleasure 
clear of the ground. The ladder thus raised serves as a lever for 
turning the mill round, which is -usually done by manual labor : some- 
times, however, more force is necessary, and a small capstan is provided, 
to draw a rope attached to the end of the ladder. This capstan is 
movable, and can be fastened at pleasure to any of the posts which are 
fixed in the ground for the purpose. When the mill is by these 
means placed in the desired direction, the ladder is let down to the 
ground ; and, its position being on the opposite side to that of the sails, 
it serves not only for ascent, and to keep the mill steady in position, 
but acts as a stay to resist the tendency of the wind to overturn it, — an 
occurrence which sometimes happens in mills of this description." 

Tower or Dutch Mills. 

In Dutch mills the dome only is turned, carrying the 
axle and sails with it into the required position ; while 
the vertical toothed wheel merely travels about the pinion, 
and the connection is not broken. In order to allow the 
dome to turn, and at the same time secure it in position, 
it is most usual to construct the tower open at the top ; 
this opening being strengthened by a wooden rim 



64 THE WINDMILL AS A PRIME MOVER. 

running completely around it. And on the upper surface 
thus exposed is a groove in which small circular metallic 
casters or rollers are placed, to turn on horizontal axes. 
The dome is made with a corresponding groove on its 
under side, so as to rest upon the rollers, and turn on 
them ; while it has also a flange, projecting downwards, 
surrounding the rim of the tower, small vertical rollers 
being here also usually fixed between the two. Thus the 
dome can be turned with a slight effort into any re- 
quired position, and by appropriate means can be fixed if 
desired. 

The turning of the dome was formerly effected by 
a toothed wheel which engaged in a rack on the inner 
side, and which was turned by means of an endless cord 
pulled by a man ; but at the present time Cubitt 's method 
is employed. This consists of a set of small sails, or an 
auxiliary windmill, placed in an upright position upon 
a long arm or frame projecting in the plane of the hori- 
zontal shaft, but on the opposite side of the dome ; the 
plane of the sails of the auxiliary windmill being nearly at 
right angles to the plane of the sails of the windmill 
proper. By their revolution, the sails turn a shaft and 
pinion, and finally act upon teeth surrounding the exte- 
rior of the dome, turning it until the wind no longer 
moves the auxiliary windmill vanes, when the sails proper 
will be exactly in their best position to receive the im- 
pulse of the wind. 

Figs. 7 and 8 represent the upper or distinctive 
portion of the tower windmill, with Cubitus method 



EUROPEAN WINDMILLS. 



65 



of bringing the sails into the wind. AA are the sides 
of the stationary part or body of the mill, which is 
either built of brick or stone, or framed in timber. CC 




Fig. 7. 



is a wooden curb attached firmly to the top of the wall, 
and upon which the rollers of the cap revolve. It is 
commonly secured either to timbers built in the brick- 



66 THE WINDMILL AS A PRIME MOVER. 

work, or to long iron rods which extend to a considerable 
distance down the walls. BBB is the cap, or head, of 
the mill, which is made of timber strongly framed to- 
gether, with a circular curb at the lower part, which 
revolves upon the one attached to the body of the milL 
•SS is the iron wind shaft. DD is the driving-wheel, 
gearing into the bevelled crown wheel N. The brake, 
employed for stopping the mill entirely, is similar to 
that described in the post mill, Fig. 5. RR, Fig. 7, is 
the ring of rollers which supports the whole weight of the 
cap, and by means of which it may be turned round upon 
the curb CC with great facility, in any direction. The 
rollers, aaaa, seen in Fig. 8, which is a plan of the cap, 
are for the purpose of keeping it in its place. They are 
attached to the upper curb, and revolve against the inner 
surface of the lower one, which is made smooth and true. 
In Fig. 7 is shown the self-adjusting cap which is turned 
round by the force of the wind acting upon the auxiliary 
fan, so contrived that the sails are always presented in the 
proper direction. A small pair of sails, M 9 are attached 
to the projecting framework, ZZ, of the back part of the 
cap ; it has a pinion upon its axle, which engages in a 
wheel, b (Fig. 8), attached to the inclined shaft cc\ and 
at the other end of this shaft a bevelled pinion is fixed, 
which works in the wheel e, on the vertical spindle of 
pinion f (Fig. 7). This latter pinion engages the cogs 
on the outside of the rim of the fixed curb ; and by 
these means, whenever the fan M is turned, it moves 
the head of the mill slowly round. It will be readily 



EUROPEAN WINDMILLS. 



67 



seen, by examining the manner in which the sails of the 
auxiliary windmill are constructed, that, when the plane 
of these sails is in the direction of the wind, they will not 
be put in motion by it ; but, if the wind varies in the least 
from the direction of the shaft of the windmill sails 
proper, it acts obliquely upon the sails of the auxiliary 



^H-t, 




Fig. 8. 



H4-H 



mill, and turns them round ; so that, on whatever side the 
wind may come, the motion conveyed to the machinery 
of the cap brings the main shaft again into the direction 
of the wind. 



Windmill Governors. 

The variations in the intensity of the wind being con- 
siderable, often so within a brief time, and sudden and 
extreme, it is necessary that windmills be provided with 
means of regulation, so that the motion of the machinery 



68 



THE WINDMILL AS A PRIME MOVER. 



be uniform, and the work performed a constant quantity, 
irrespective of the varying pressure of the wind. At one 
time this was effected by the use of a friction strap 
applied to the outside of the wheel on the wind shaft, 
but this soon gave way to the method of regulation by 
change of extent of surface offered to the wind by in- 
crease or decrease of the amount of canvas of the sail. 
The latter was formerly accomplished by having a rope 
attached to each sail, or having the canvas made in three 
portions, controlled by separate ropes ; and much trouble 
and delay were occasioned, as the mill required to be 
stopped, and a man had to ascend the sails separately to 
take in or let out the canvas. A description of such a 
mill is given in Fairbairn's "Mills and Millwork," as fol- 
lows : — 

" The tower was of brickwork, and appeared to be eighteen feet 
diameter at the base, and about fifteen feet at the top, and about twenty- 
two feet high. The four wings were about thirty-five feet diameter, and 
of a rectangular shape, about fifteen feet long and five feet broad. The 
surface exposed to the wind was increased or diminished by the appli- 
cation of canvas sails, whose spread could be raised by reefing or 
twisting up the extreme end of the sails when the mill was in a state of 
rest. The main axle, which was octagonal in form, was constructed 
of oak, about fifteen inches diameter at the neck, and about ten inches 
at the rear end. The front of the axle, which received the arms, was 
square ; and the two pairs of arms did not intersect the axle in the same 
plane, the one pair being in advance of the other. All the arms butted 
against the axle, and were united to it by side pieces, which were securely 
bolted to the arms and through the axle, which rendered mortising 
unnecessary, and preserved the strength of the shaft. The bearing in 
which the neck of the axle revolved, seemed to be formed of some hard 



EUROPEAN WINDMILLS. 69 

wood, probably lignum-vitae, and was lubricated with soft soap and 
plumbago. The rear end of the shaft was fitted with an iron gudgeon, 
about three inches diameter, secured by iron hoops and wedges. 
About the middle of its length, this axle carried a face wheel about four 
feet diameter, which was constructed entirely of timber ; its arms were 
mortised through the axle, and secured by iron hoops round the rim, 
which formed the bearing-surface for the friction strap or brake for 
arresting the speed of the mill. The teeth of this wheel, which were 
about three and a half or four inches broad, and four and a half pitch, 
geared into a trundle or pinion about fourteen or fifteen inches diam- 
eter, fixed at the top of a long vertical wrought-iron shaft about two 
and a half inches square, which was coupled at its lower extremity to 
the rhynd on the top of the millstone spindle ; the long shaft being 
steadied by a bearing near the centre of its length, to prevent any jarring 
or vibration being communicated to the revolving millstones. . . . When 
the mill was set a-going, the wings performed twenty-nine revolutions 
per minute when loaded; and the extremity of the sails acquired a 
velocity of about thirty-two hundred feet per minute, or nearly thirty-five 
miles per hour." 

In 1780 Mr. Andrew Meikle devised, for reefing the 
sails when the mill was in motion, an ingenious applica- 
tion of the centrifugal governor ; viz., a sliding piece, 
which operated upon rollers placed transversely with the 
arms, and wound up or reefed the canvas when the sails 
attained too great a velocity. The unfurling of the sails 
or increasing their speed was accomplished by a weight 
which actuated a rod passing through the centre of the 
main axle, and operated centripe tally on the sliding- 
frames, and then unwound the canvas when the motion 
of the sails was too much retarded. Fairbairn defines 
this as the first successful automatic reefing apparatus 



70 THE WINDMILL AS A PRIME MOVER. 

applied to windmills, and says, that, when the wind was 
not squally, it imparted to the mill a precision of motion 
little inferior to some of the then modern steam-engines, 
and that, by varying the weights for unfolding the sail, 
the power of the mill could be increased or diminished 
with facility. 

In 1807 Mr. William Cubitt devised an excellent 
method of reefing the sails of windmills, by introducing 
movable shutters in the sails of the mills ; which shutters 
were closed by a governor, operating upon a rod passing 
through the centre of the main axle. These shutters 
were suspended on points fixed almost one-third of their 
breadth from one side ; and, when the wind was blowing 
too strong, it opened the shutters, and allowed a portion 
of the wind to pass through them, and so also checked 
the velocity of the mill. 

Sir William Cubitus devices for governing, which 
were satisfactory and effective, are illustrated in Figs. 9, 
10, and 1 1 ; which cuts, as well as the following descrip- 
tion, we extract from Barlow's " Encyclopaedia of Arts, 
Manufactures, and Machinery." 

" Fig. 9 represents a set of vanes, in which AA shows the valves 
turned to the wind, and their surfaces exposed at right angles to it ; BB 
exhibits the vanes as close-reefed, with their edges to the wind, so that 
it can have no effect upon them, except on their edges. In the drawing, 
the vanes are exhibited as having the whip down the middle, with valves 
on both sides ; but it is evident that the vanes may be constructed with 
the whip placed in the usual way, and have valves on one side only. 

" Fig. 10 is a section through the wind shaft, exhibiting the apparatus 
for regulating the vanes. A is the wind shaft, which is bored through 



EUROPEAN WINDMILLS. 



7* 



the centre, to admit an iron rod, B, to pass freely through it ; one end 
of this rod has a knol or onion on it, which turns in a box, r,-so that 
it can be moved endwise while it continues to revolve. The box c is 
fastened to a toothed rack, D, whose teeth engage those of a pinion, E, 



A 

Fig. 9. 




upon the spindle of which is a sheave, F, with a groove on its circum- 
ference to receive a rope, G, to which is hung the weight W. This 
weight serves to regulate the force of the wind upon the valves, and 
may be adjusted to the nature of the work to be performed by the 
milL On the other end of the rod is fixed a plate of iron, K, with ears 



72 



THE WINDMILL AS A PRIME MOVER. 



upon it, projecting from each side, in which are fixed the bridles or 
leaders/Z, Z, which permit the levers M 9 M, to describe a curve with 
their ends, while the iron rod B moves in a straight line. N 9 N, are two 
uprights or props, on the ends of which the levers M, M, move, and com- 
municate the motion of the iron rod B to the racks P, P. These racks 
engage the pinions Q, Q, on the axis of which (according to one method 
here described, Fig. 10) is fixed a strong iron lever or crank, C : the 
end of this is attached to a slider, S. Each vane has a small lever 
projecting from it, which is fixed in the slider by a pin or gudgeon ; so 
that, by the motion of the slider, the vanes present a different angle to 
the wind. 

"The other method of regulating the vanes is shown in Fig. n 5 
where, instead of levers, the vanes have a pinion attached to them, 
which engages the teeth of a rack or slider, T. 

"The operation of this apparatus will be readily understood by 
imagining the rope G pulled down so as to cause about three-quarters 
of a revolution of the sheave F. The pinion E will put in motion the 
rack D and rod B, which brings the lever into the position represented 
by the dotted lines. The rack P will have turned the pinions till the 
slider 5 or T (according to whichever method may be used) brings 
the vanes into such a position that their whole surface is presented 
to the wind ; therefore, if a weight be hung upon the line G, it will keep 
the surface of the vanes to the wind until the strength of it is such as 
to raise the weight, when the vanes will be more or less opened until 
the pressure upon the inclined surface is reduced so as to balance the 
weight. By this means the force of the wind beyond that sufficient to 
raise the weight will not produce any additional velocity, and a degree 
of regularity will be attained which can never be produced by the 
ordinary method." 

Other methods of governing the area of the sails 
according to the force of the wind have been devised 
and put into practice ; but, since the above suffice to indi- 
cate the main types used, our object is accomplished, and 



EUROPEAN WINDMILLS. 



73 



we feel justified in limiting our presentation of European 
mills at this point. More especially is this permissible, 
since windmills of the European type are rapidly and 
deservedly being superseded by the American class of 
mill, for reasons briefly outlined in the next chapter, 
which treats more particularly of the various types and 
of the construction of American windmills. 



74 ' THE WINDMILL AS A PRIME MOVER. 



CHAPTER V. 

AMERICAN WINDMILLS. 

Classification of Types. — Side- Vane Governor Mills. 

American windmills differ from the European mills, 
already described, most conspicuously in the form of 
wheel receiving the impulse of the wind. Instead of the 
small number of sails of large width, common to the 
European or Dutch mills, the American wheel is made 
up of a great number of blades or slats of small width. 
This, of itself, gives an entirely distinct appearance to 
the American wheel, since it resembles a closed surface 
as compared to the large open spaces between the arms 
of the European mill, though, of course, ample room is 
provided between the slats to permit the free escape of 
the impinging air. This division of the receiving-surface 
of the mill into a large number of narrow sections, which 
in turn are sustained by truss rods from an extension of 
the main shaft, enables a much smaller aggregate weight 
of parts for a desired strength, size, and capacity of mill ; 
so that the American windmill is lighter in weight, as well 
as in appearance, than the European mill. The angles 
employed are not as advantageous in the former as in the 



AMERICAN WINDMILLS. 75 

latter ; but the surface presented for a given diameter is 
so much greater in the American wheel, as to more than 
compensate for this defect. No better proof of the 
superiority of the American windmill need be given than 
the fact that it is rapidly replacing the Dutch type in 
Germany, France, and England. In all of these coun- 
tries the American type is now being manufactured on a 
large scale, especially so in Germany. The American 
windmill, too, is being extensively used in English col- 
onies, on the recommendation of English engineers. 

In presenting American windmill construction, it will 
not be our aim to give an account of every special variety 
of mill in the market, but rather to confine ourselves to 
an ample illustration of the leading features of the several 
types which distinguish American practice. Our atten- 
tion will be directed mainly to the vertical mill, which 
is the leading class in America, and which, in point of 
economy and availability, of course so far surpasses the 
horizontal mill, as to make it unnecessary to do more 
than to give this brief reference to 'the latter type.* 

The several types of American windmills are charac- 
terized by the form of wheel, and the method of regu- 
lation or governing employed to vary the extent of the 
surface presented to the wind, so that a uniform power 
and a uniform rate of revolution may be "obtained under 
varying velocities of wind. The two principal types may 
be distinguished respectively as the sectional wheel with 
the centrifugal governor and independent rudder, and 

* See p. 55. 



76 THE WINDMILL AS A PRIME MOVER. 

the solid wheel with the side-vane governor and inde- 
pendent rudder. In both types, the rudder brings the 
wheel into the direction of the wind. This rudder is a 
large, strong vane, projecting opposite the shaft and the 
wheel. The plane of the rudder is vertical, and perpen- 
dicular to that of the wheel ; so that the wind, however 
shifting, acts directly upon the rudder to bring the plane 
of the wheel normal to the wind. In the first type, 
the flying-out or receding of weighted arms cause the 
slats of the wheel to revolve, in sections, on pivots in 
the windmill arms or frame, thus bringing the slats or 
the surface of the wheel more or less normally to the 
direction of the wind. In the second type, there is a 
vane nearly in the plane of, and directly behind the solid 
wind wheel, which vane is attached to the bearing of 
the shaft. When the velocity of the wind increases, the 
increased pressure on this side vane causes the wind 
wheel to turn bodily away from the wind, the whole 
wind wheel and bearing rotating on a horizontal turn- 
table, which forms part of the support of the mill. Thus, 
less effective surface is presented to the wind until the 
wind decreases, when the lowering of a counterbalancing 
weighted lever, raised previously by the turning of the 
wheel when, the pressure was high, causes the wheel, 
together with its accompanying side vane, to turn more 
normally to the wind. 

Besides these two leading types, there are others. In 
a third type, a solid wind wheel is employed ; but the 
regulation is effected by placing the rudder, or its 



AMERICAN WINDMILLS. JJ 

equivalent, at a slight angle to the centre line of the 
shaft, so that the windmill is never entirely normal to 
the direction of the wind. As the wind pressure increases 
materially, the rudder is thrown more to the side, and the 
wheel more out of the wind. 

In a fourth type, no rudder at all is employed, and the 
pressure of the wind on the wheel itself is relied upon to 
bring the wheel into the proper direction. These latter 
two types of governing are not at all sensitive, but 
answer satisfactorily for smaller mills, to which their use 
is restricted. 

The two leading types, satisfactory in all sizes, are 
the solid wind wheel with side- vane regulation, and the 
sectional wind wheel with centrifugal governor regula- 
tion ; both having independent rudders, to bring the 
windmill exactly normal to the direction of the wind. 
Either of these two types of governing is applied to 
the smallest and the largest sizes of windmills, and acts 
with sufficient accuracy and promptness to place the 
American windmill in the rank of reliable automatic 
engines. 

It will be readily understood that the centrifugal 
governor is somewhat speedier and more sensitive in 
action than the side-vane governor, but the former type 
of mill has the disadvantage of the wear and tear of the 
pivots. Practically, however, the side-vane governor is 
sufficiently sensitive and speedy in action ; while, on the 
other hand, the wear and tear of the centrifugal-governor 
type, of proper construction, has not been found to be a 



78 THE WINDMILL AS A PRIME MOVER. 

material objection in use. As a fact, the choice between 
these two types is narrowed to very close limits, and 
both types are in use to an almost equal extent, and give 
an almost equal degree of satisfaction. 

The main point in the selection of a windmill, as far 
as its reliability of action and durability are concerned, is, 
to insist on the use of good materials and workmanship ; 
and, though both these requisites have a fair representa- 
tion in this country, there is a sufficient amount of poor 
work done to make it a necessity to call special attention 
to this prime need. 

Side- Vane Governor Mills. 

The Corcoran Mill. — Among this class of mill, there 
is none superior and justly more highly esteemed than 
that manufactured by Mr. A. J. Corcoran of New- York 
City. 

Fig. 1 2 well presents the main features and details of 
Mr. Corcoran's windmill for water supply. The iron- 
work is indicated by numbers, and the woodwork by 
letters. IJK represents a twelve-foot wind wheel, N 
the side vane, M the flexible rudder, 26 the weighted 
lever, 10 the connecting-link, 24 the slide ; all concen- 
trated in the iron frame 1 . 1 7 is the supporting-piece, 
faced on top, and bored out to receive the frame 1, 
having flange on top to hold lubricating compound, and 
being secured to the mast by four bolts. A flange also 
extends halfway over the top of the mast. At 18 is an 




Fig. 12 



80 THE WINDMILL AS A PRIME MOVER. 

additional support, bored out to fit i, and secured to the 
post by two bolts. The main frame of the mill consists 
of a piece of hydraulic tubing, with a bearing to support 
the wind-wheel shaft, resting on an anti-friction washer, 
which is held in place by cap .16. The object of this 
tubing, coming down the mast as far as the windmill 
arm /, is to give the main frame of the windmill a more 
equal leverage with a strain brought upon the arm, and 
thereby prevent any rocking motion of the mill on the 
mast in unsteady winds. At 27 is the rudder bar, and 
at 28 the truss rods which support the rudder vane. 
The ends of the wrought-iron connecting-link 10 are 
babbitted to fit steel pins on the crank wheel and slide. 
The crank wheel has various centres, to admit of different 
strokes of pumps, with a given diameter of wind wheel. 
The wrought-iron lever 26 is bolted to the piece 19, 
which works on the stud pin on the rear of the frame. 
The chain 35 is connected to the stop rod 25, which is 
secured to a small lever on the mast, near the ground. 
By bearing down on the lever, the wheel is brought 
around parallel with the rudder, thus presenting only the 
ends of the slats to the wind. The arms / are bolted 
to a centrepiece, 4, as shown ; this spider form of 
support 4 being a characteristic part of all American 
vertical windmills. This form of wind wheel is known as 
the " rosette " pattern. In high winds, the increased 
pressure on the independent side vane causes the wind 
wheel to gradually turn around, away from the wind - 
raising the weighted lever 26. This lever, in turn, falls 



AMERICAN WINDMILLS. 



81 




Fig. 13. 



82 THE WINDMILL AS A PRIME MOVER. 

as the wind pressure again decreases, and thus the wheel 
is again brought more normal to the wind. Thus a 
uniform rate of speed is maintained, proportioned to the 
position of the weight 13 on the lever. 

The parts of this mill are accurately fitted to standard 
gauge, and are therefore interchangeable. 

In Fig. 13 is illustrated a Corcoran Windmill as 
applied to railway water stations. A is the pump timber, 
B the well curb, -Fthe pump pitman, G the stopping-rod, 
1 the foot valve, 2 the suction valve, 3 the pump, 4 the 
globe valve, 5 the delivery pipe, 6 the valve for emptying 
tank, and 7 the overflow pipe. This illustration also 
shows the wooden tower of the Corcoran Windmill for 
sizes from sixteen to forty feet diameter of wheel, with the 
camber of its side beams to secure stiffness and lateral 
strength. A cheaper method of erecting a tower for wind- 
mills of from eight and a half to fourteen feet diameter 
of wheel is shown in Fig. 14, which explains itself. 

Fig. 15 (p. 85) shows a Corcoran Geared Windmill, 
designed for driving machinery. The windmill is made 
in sizes of from sixteen to thirty feet diameter of wheel. 
The illustration shows the method of transmitting the 
power from the windmill by shaft No. 26 to the pulley 
No. 13, as well as the general construction and appear- 
ance of the ironwork, of which material the *mill is 
principally composed, the wind wheel and the rudder 
vane being the only parts of wood. 

The regulating or governing principle of this mill is 
substantially the same as that of the pumping-windmill, 




Fig. 14. 



84 THE WINDMILL AS A PRIME MOVER. 

shown and described in Fig. 1 2 ; the balls and chain 
attached to No. 16 of this mill being equivalent to the 
weight bar No. 26, the weight No. 13, and the quadrant 
No. 19, of the pumping-mill. 

The regulation of this mill is accomplished independ- 
ently of any of the parts used for transmitting the power. 
All the parts of the same size of this mill interchange, all 
journals are turned to measurement of solid calipers, the 
bearings are babbitted on mandrels prepared for the work, 
and the holes are drilled by template. The material em- 
ployed consists mainly of malleable iron. The shafting 
is cold-rolled, and steel pins are used for all the joints. 

In this mill, the upright and line shaft are all secured 
in one iron frame, and so fitted that they cannot get out 
of line during erection or during action, the weather not 
affecting the same, as is the case where wood is em- 
ployed for the main frame. 

Referring to the cut (Fig. 15), Nos. 4 and 5 are gears 
made of Bessemer steel, and are graduated for speed at 
the nxe of one revolution to three. The vertical shaft 
No. 8 revolves in Babbitt-metal bearings No. 6, and in 
No. r. at point shown by No. 3. No. 21 is a dome 
enclosing Nos. 4 and 5. It is faced in a lathe, and bolted 
to No. 1. No. 22 is secured to No. 21 by a flange and 
bolts, same as that used for a shaft coupling, and is cone- 
shaped, in order to prevent its getting out of line should 
any of the bolts become loosened. Nos. 21 and 22 cover 
the gears, protecting them from sleet or ice, or from the 
entrance of any thing injurious. At the same time, they 




Fig. 15. 



86 THE WINDMILL AS A PRIME MOVER. 

form a strong and substantial support for the upper end of 
the vertical shaft, also keeping No. 5 in place ; and in the 
event of repairs being necessary, or an alteration of the 
shaft No. 8, the latter can be easily removed, without tak- 
ing down the mill, by taking off the cap or dome No. 22. 

The turn-table No. 1 rests and turns on a step 
casting, No. 3, which has a deep recess for receiving the 
end of No. 1. It also has a steel friction washer ; and the 
entire weight of the mill, supported by No. 1 , rests and 
turns on this steel friction washer, sustained by No. 3. 
The windmill may be stopped and started by raising or 
lowering a wooden rod connected with No. 16. This 
lever is operated by a windlass placed in the bottom of 
the tower ; and, by raising the wooden rod and cross-head 
No. 16, the rings No. 19 and 20 move on the rods 
No. 18, the rings being connected by a chain with the 
half-circle board E, a part of the rudder D. 

The upright shaft 7-1, and the horizontal shaft 12, 
are supported by a combined bearing ; making it impos- 
sible for either to get out of line. The upright shaft has 
a steel lower end, revolving in a copper friction washer 
No. 8. No. 12 is made of cold-rolled shafting or of steel. 

An important feature of the mill is the safety lever 
/sand the clutch coupling No. 14. No. 15 is a forked 
lever, and works in a groove in No. 14. The shafts 7-1 
and 8 are made in two pieces, united by the coupling 
No. 14; the upper half working on a feather or spline, 
and the lower half being firmly keyed to the coupling. 

It is, of course, very important that there should be a 



AMERICAN WINDMILLS. 87 

means of stopping the motion instantly in case of acci- 
dent, should the belt slip off, or for other reasons. Any 
-windmill can be stopped by pulling it out of the wind ; 
but, as this does not do away with its momentum, it is 
some time before the line shaft 12 comes to a state of 
absolute rest. With this mill, the safety rope G is brought 
to a convenient point in the tower or shop, where any one 
can pull down on it ; and doing so separates the coupling, 
lifting the upper half from the lower, and allows No. 8 to 
revolve, while No. 7-1 and all below it stop instantly. 

This method also makes it unnecessary to shift a 
heavy belt to stop the machinery in the shop. 

The number of arms A used in the wind wheel 
depends upon its size, and varies from eight to twelve. 
They are securely bolted to the hub No. 25, and sup- 
ported by the front braces B, fastened to the brace head 
No. 27, connected with main shaft No. 26, and supported 
by girts C. The sections of the wind wheel — or fans, 
as they are not uncommonly called — are connected to 
arms A by malleable iron clips 32, 33, 34, 35, making 
from two to eight complete circles around the wind 
wheel when all the sections are in place. 

The Eclipse Windmill, manufactured by the Eclipse 
Windmill Company at Beloit, Wis., is identical in prin- 
ciple with the Corcoran mill, just described. Indeed, the 
Eclipse is the parent of the Corcoran mill, and the latter 
but a refinement of the former, the two differing only in 
a few minor details. The main difference is in the grade 
of construction. The Corcoran mill is specially designed 



88 THE WINDMILL AS A PRIME MOVER. 

for a high class of trade, while the Eclipse is built for a 
wider and more general use. But inasmuch as the 
principle and main construction of the two mills are alike, 
it is not necessary to detail the Eclipse mill at length, as 
the illustrations and description of the one will virtually 
answer for the other. Suffice it to say that the Eclipse 
is a good reliable mill, has a large representation on the 
railroads of the country, besides its extended use for 
other pumping and power purposes, and that it is manu- 
factured in large numbers in Germany. The fact should 
also be noted, that the Eclipse Windmill Company manu- 
factures a larger number of side-vane governor mills than 
any other firm, and is, indeed, one of the two largest 
windmill concerns in the country. The other concern, 
manufacturing a different type of mill, is referred to on 
the next page. 



AMERICAN WINDMILLS. 89 



CHAPTER VI. 

AMERICAN WINDMILLS (CONTINUED). 

Centrifugal -Governor Mills. 

Of the centrifugal-governor mills, the Halladay, 
manufactured by the United-States Wind Engine and 
Pump Company of Batavia, 111., is most extensively used 
in America ; and its excellent record and extensive use 
make it stand out pre-eminent among centrifugal -governor 
mills. 

Fig. 16 clearly shows the general construction and 
method of operation of the mill. A, the bed plate, is 
a strong casting, resting on, and firmly bolted to two 
masts in the tower, and further secured by the two 
braces E, E. Upon this revolves the turn-table B> held 
in position by bolts K, with oblong heads, which reach 
under the bed plate. The turn-table moves on rollers, 
which allow it to turn freely as the wind changes its 
direction. These rollers run on a lathe- turned track, and 
both are protected from the weather by flanges on the 
turn-table. The spider CC y to which are bolted the arms 
or spokes of t^ie wind wheel, is firmly keyed to the main 
shaft, which rotates in Babbitt-lined boxes on the turn- 




Fig. 16. 



AMERICAN WINDMILLS. 9 1 

table. On the inner end of this shaft is keyed the crank- 
plate M, to which is attached the pitman L. By means 
of the post attachments, consisting of sleeve box S, 
swivel box X> and sliding-boss Z> connection is so made 
between the pitman and the pump, that the revolving of 
the turn-table upon the bed plate will not twist or cramp 
the connections, or prevent sails being spread or furled, 
by means of shut-off rod R. 

The regulating-gear consists of the sliding-head /?, 
elbows Y> and their connections. The inner end of each 
elbow is connected to the sliding-head by a link, the 
connections from the outer ends to the sails being made 
by means of regulating-rods. 

On the outer ends of the regulating-rods are the 
governing-balls or regulating-weights, the action of 
which is the same as the governor on a steam-engine, 
causing the sails to present less surface to the wind as 
its velocity increases. 

The weight W, on forked lever F, acts in opposition to 
the regulating-weights, causing the sails to present more 
surface to the wind as the power of the wind decreases. 
The sails may be furled, and the mill stopped and made 
to stand still, by pulling down on shut-off rod R. The 
regulating-gear is comparatively simple, securing a direct 
connection with each sail, and direct action of the regu- 
lating-weights on the sliding-head and its connections, 
thereby giving positive movement to all the parts. 

Fig. 1 7 gives the detail of the iron-work in the Hal- 
laday Mill, i represents the turn-table ; la, the rear cap 




Fig. 17. 



AMERICAN WINDMILLS. 



93 



on turn-table ; 16, the front cap on turn-table ; ic 9 front 
box on turn-table ; id, rear box on turn-table ; le, clamp 




bolt; 2, bed plate; 20, anti-friction rolls and carriage; 3, 
forked lever; 30, weight on forked lever; 4, main shaft; 



94 THE WINDMILL AS A PRIME MOVER. 

5, spider; 50, elbow; 5^, elbow collar; 6, back plate; 6a, 
shoes on back plate ; 6b, front-plate and slide-head rods ; 
6c, link connecting back plate to elbow ; 7, chain pulley ; 
ya, balance weight and chain ; 8, crank plate ; Sa, crank 
pin ; 9, pitman ; ga, top pitman box ; 96, lower pitman 
box ; 10, stub end ; 10a, sleeve on stub end ; io£, sliding- 
boss on stub end; 10c, swivel box; 10*/, sleeve box; 11 
(see also Fig. 18), regulating- rod ; 11 a, set iron on regu- 
lating-rod ; n£, regulating- weight ; 12, angle box; 13, 
tilt-bar socket; 13a, tilt-bar lever; 14, flat-bar connec- 
tion ; 14a, force-pump connection; 15, slide fork. 

Fig. 18 represents the detail arrangement of the fan 
of the 1 2 -foot mill. 

The angles of weather of the slats vary from 30 to 45 
degrees, depending upon the size and kind of windmill. 
In the geared mills the slats are set flatter than in the 
pumping mills, as they are run more rapidly. 

Fig. 19 shows the general arrangement of the geared 
mills. 

The Halladay Windmill is in more extensive use in 
America for railway water stations than any other mill, 
and the general view presented in Fig. 20 is therefore of 
interest. 

The manufacturers claim that hundreds of their wind- 
mills have been in active use on railways for over twenty 
years, at an expense not exceeding an average of five 
dollars per year for oil and repairs. We see no reason 
to question the correctness of this statement. 

This mill is constructed in Germany, by Friedrich Filler 




Fig. 19. 




Fig. 20. 



AMERICAN WINDMILLS. 



97 



of Eimsbiittel, Hamburg, who does quite an extensive 
business in its manufacture. We illustrate, in Figs. 21 
and 22, a few interesting applications made by Mr. Filler, 
which speak for themselves. 




Fig. 21. 



The Althouse Windmill. — Figs. 23, 24, and 25 illus- 
trate the well-known centrifugal-governor mills, manufac- 
tured by Messrs. Althouse, Wheeler, & Co., of Waupun, 
Wis. The rudder is not shown in any of the cuts. Fig. 
23 is a 10-foot mill, as constructed for pumping-purposes. 
Fig. 24 is a 14-foot geared mill, as constructed for power 
purposes. In this case the rudder is very small, and 
placed in front of the wheel, and parallel to the main 



9 8 



THE WINDMILL AS A PRIME MOVER. 



shaft. Fig. 25 shows the iron-work in detail. Like 
figures apply to like parts in the several illustrations.. 
1 represents the bedplate; 2, the step; 3, the turn- 
table ; 3c, turn-table roller block ; 3*, turn-table rollers ; 




Fig. 22. 



4, turn-table sleeve: 5, turn-table sleeve clip; 6, maift. 
shaft ; 8, spider ; 9, crank wheel ; 10, crank pin ; 11, slide 
head; 14, front slide ; 17, chilled clutch ring (2 pieces) ; 
20, clutch oil cup ; 21, forked clutch bar ; 24, weight 
lever; 27, weight; 28, truss posts; 30, truss rod; 33, 
pitman; 34, pitman upper box; 36, swivel; 37, swivel 
collar ; 38, wood-rod attachment ; 39, section levers ; 40, 
section levers, links straight; 41, section levers, curved; 



AMERICAN WINDMILLS. 



99 




26 aJ^aa 



Fig. 23. 



AMERICAN WINDMILLS. IOI 

42, arms; 43, arm irons; 46, section fans; 47, section 
centre-bar castings ; 48, section inner-bar castings ; 49, 
section rods; 55, splice irons for wood rods; 56, wood 
pitman rods; 57, pump attachment; 59, arm weight; 60, 
hand lever. 

The Adams Windmill, constructed by the Marseilles 
Manufacturing Company, Marseilles, 111., is shown in Fig. 
26. It is identical in principle with the Halladay Mill, 
with the exception that the centrifugal governor, consist- 
ing of weighted lever, has no slide head as a counterbal- 
ancing mechanism, but the regulating-rods leading from 
the centre of the section bars are attached to a cylindrical 
friction wheel placed on the rear of the hub. This fric- 
tion wheel consists of a curved spring, set for a given 
speed, which, when this speed is exceeded, is curled up, 
and retards the motion of the cylinder to which it is 
attached, thus causing the rods to pull the sails more out 
of the wind. When the wind again decreases, the spring 
uncurls, and the sections, actuated by the weighted lever, 
again enter more into the wind. 



102 THE WINDMILL AS A PRIME MOVER. 




Fig. 25. 



AMERICAN WINDMILLS. 



I03 




Fig. 26. 



104 THE WINDMILL AS A PRIME MOVER. 



CHAPTER VIL 

AMERICAN WINDMILLS : OTHER TYPES, -r- VELOCITY REGULA- 
TION, ETC. 

The Buchanan Windmill. 

This wheel, shown in Fig. 27, belongs to the class 
of mills which depend for their regulation upon the 
natural tendency of the wheel to go into the direction it 
turns, as the velocity of wind increases materially. In the 
detailed vietf showing the mechanism, A is a wrought- 
iron pipe, upon which the whole structure is supported; 
B is the main frame which turns on the pipe A\ D \$ 
the governing device. As will be seen, a lug projecting 
from the side of the lever bears upon the inclined pro- 
jection on the main frame : so that, when the mill is 
thrown out of the wind, the weight-lever is elevated ; 
and as the wind decreases from its high velocity, the 
lowering of the weighted lever again brings the wheel 
into the direction of the wind. G is the derrick cap, F 
the cross-head, / a spring to cushion against the sudden 
throwing of the mill out of the wind, — a necessity in the 
class of mills which are governed by the velocity action 
of the wheel itself. 



AMERICAN WINDMILLS: OTHER TYPES. 



I05 



A feature of this mill different from all others is the 
method of fastening the slats to the section bar of the 




Fig. 27. 

wheel. While in other mills the slats are secured in 
grooves in the section bars, by means of nails, the 



I06 THE WINDMILL AS A PRIME MOVER. 

slats in the Buchanan Mill are secured to the section bars 
by wire clips. 

The Woodmanse Windmill. 

This mill, manufactured by the Woodmanse Windmill 
Company, .Freeport, 111. (see Fig. 28), has a solid wheel, 
and the rudder in the centre line of the main shaft, to 
bring the wheel into the line of the wind. Its change of 
extent of surface, according to the force of the wind, is 
caused by a natural tendency of the wheel, running at a 
high rate of speed, to move bodily in the direction that 
the wheel turns. Of course this action is felt materially 
only at high speed, which precludes the possibility of 
such mode of regulation for large mills. In fact, it is 
used with good effect only for small pumping-mills, where 
it gives satisfaction. 

It will be readily understood, that, as this wheel shifts 
out of the wind at high speed, the weight shown in Fig. 
28 is lifted. Its lowering when the wind decreases, again 
brings the wheel into the direction of the wind. This 
windmill is well constructed, and is therefore a good 
machine of the type it represents. 

The Stover Windmill. 

The Stover Windmill, manufactured by the Freeport 
Machine Company 0/ Freeport, 111., is similar to the mill 
shown in Fig. 28, except that the rudder, instead of 
being in the centre line, stands off from three to six 
inches from the main shaft, but is parallel to it. The 




". ■ ■ 

k ttllilliii^itii!»W!VM^\ftK.. ......,.v-.:;* ; ,. 



Fig. 28. 




Fig. 29. 



AMERICAN WINDMILLS: OTHER TYPES. IO9 

distance between the planes of the rudder and of the 
shaft increases with the size of mill. 

This enables a speedier getting-out of the wind, 
inasmuch as a larger portion of the wheel stands off 
from the centre line of the rudder ; but it has the disad- 
vantage of the wheel never being fully in the wind. 
This wheel runs to the left, while all other mills run to 
the right. 

The Champion Windmill. 

Fig. 29 illustrates a ten-foot pumping-mill, in which 
there is no rudder. This mill, known as the Champion, 
is manufactured by Messrs. Powell & Douglas, Wauke- 
gan, 111. The regulation of the extent of surface is on 
the centrifugal-governor plan. The mill is brought into 
the direction of the wind by the natural tendency of the 
wheel to turn into that position ; the wheel being placed 
behind the mast, instead of in front, as is the customary 
practice. Inasmuch as the face of the wheel is toward 
the mast, and the sections turn in the same direction, the 
wheel, as will be seen in Fig. 29, is a considerable dis- 
tance from the axis of the mast ; and consequently there 
is an overhang, which has a tendency to bring an unequal 
strain on the main bearing and turn-table. The face of 
the wheel being behind the mast, and most of the regu- 
lating-gear in front of the wheel, the wind is to some 
extent broken before it strikes the wheel. 

In Fig. 29, 1 represents the turn-table ; 2, the bed 
plate; 3, the step (two pieces) ; 4, main box; 5, cap of 




Fig. 30. 



AMERICAN WINDMILLS: OTHER TYPES. Ill 

main box ; 6, crank plate ; 7, connecting-rod ; 8, cap of 
connecting-rod ; 9, pipe pitman ; 10, pitman connection ; 
1 1 , wood-rod splice ; 1 2 , pump connection ; 1 3 , twin levers ; 
14, slide head; 15, slide-head segments; 16, slide-head 
ring; 17, spider; 18, outside hub ; 19, spoke shield ; 20, 
socket on spoke end; 21, gudgeons of sails; 22, brace 
connection on sail ; 23, governing- weight ; 24, fulcrum of 
governing-lever; 25, tower-post weather shield. 

In Fig. 30 is shown a geared wind wheel of the same 
type, in which a vane is placed at an angle to the centre 
line of the shaft. The vane is to offset the tendency of 
the wheel to go with the strain of the gear, and is found 
a necessity in geared mills of this type. It is not neces- 
sary in pumping-mills, with the crank motion, as the 
strain then is entirely vertical. 

The Regulator Windmill. 

The Regulator Windmill, manufactured by the Sand- 
wich Enterprise Company, Sandwich, 111., shown in Figs. 
31, 32, and 33, has a solid wind wheel, but no rudder, 
and runs behind the mast, differing in the latter respect 
from all other solid wind wheels. The regulating-gear 
consists of a small vane on a large lever directly in front 
of the wheel, the vane portion projecting outside of the 
wheel. This vane is inclined to the plane of motion of 
the wheel, being set at the same angle as the slats. In 
addition, this vane has a projecting fan at right angles to 
the vane itself, so as to make the vane catch the wind 




Fig. 31. 




Fig. 32. 



H4 



THE WINDMILL AS A PRIME MOVER. 




Fig. 33. 



106 THE WINDMILL AS A PRIME MOVER. 

slats in the Buchanan Mill are secured to the section bars 
by wire clips. 

The Woodmanse Windmill. 

This mill, manufactured by the Woodmanse Windmill 
Company, .Freeport, 111. (see Fig. 28), has a solid wheel, 
and the rudder in the centre line of the main shaft, to 
bring the wheel into the line of the wind. Its change of 
extent of surface, according to the force of the wind, is 
caused by a natural tendency of the wheel, running at a 
high rate of speed, to move bodily in the direction that 
the wheel turns. Of course this action is felt materially 
only at high speed, which precludes the possibility of 
such mode of regulation for large mills. In fact, it is 
used with good effect only for small pumping-mills, where 
it gives satisfaction. 

It will be readily understood, that, as this wheel shifts 
out of the wind at high speed, the weight shown in Fig. 
28 is lifted. Its lowering when the wind decreases, again 
brings the wheel into the direction of the wind. This 
windmill is well constructed, and is therefore a good 
machine of the type it represents. 

The Stover Windmill. 

The Stover Windmill, manufactured by the Freeport 
Machine Company of Freeport, 111., is similar to the mill 
shown in Fig. 28, except that the rudder, instead of 
being in the centre line, stands off from three to six 
inches from the main shaft, but is parallel to it. The 




Fig. 28. 




Fig. 29. 



AMERICAN WINDMILLS: OTHER TYPES. IO9 

distance between the planes of the rudder and of the 
shaft increases with the size of mill. 

This enables a speedier getting-out of the wind, 
inasmuch as a larger portion of the wheel stands off 
from the centre line of the rudder ; but it has the disad- 
vantage of the wheel never being fully in the wind. 
This wheel runs to the left, while all other mills run to 
the right. 

The Champion Windmill. 

Fig. 29 illustrates a ten-foot pumping-mill, in which 
there is no rudder. This mill, known as the Champion, 
is manufactured by Messrs. Powell & Douglas, Wauke- 
gan, 111. The regulation of the extent of surface is on 
the centrifugal-governor plan. The mill is brought into 
the direction of the wind by the natural tendency of the 
wheel to turn into that position ; the wheel being placed 
behind the mast, instead of in front, as is the customary 
practice. Inasmuch as the face of the wheel is toward 
the mast, and the sections turn in the same direction, the 
wheel, as will be seen in Fig. 29, is a considerable dis- 
tance from the axis of the mast ; and consequently there 
is an overhang, which has a tendency to bring an unequal 
strain on the main bearing and turn-table. The face of 
the wheel being behind the mast, and most of the regu- 
lating-gear in front of the wheel, the wind is to some 
extent broken before it strikes the wheel. 

In Fig. 29, 1 represents the turn-table ; 2, the bed 
plate; 3, the step (two pieces) ; 4, main box; 5, cap of 



n8 



THE WINDMILL AS A PRIME MOVER. 



fulcrum at G } and coupled at its upper end by the link S 
to the rudder. The fulcrum is supported on a bracket, 
N, on the frame B of the mill. This lever resists the 
action of the wind on the wheel until the pressure is 







u 



greater than what the lever is loaded for, when the wheel 
swings around on the turn-table, presenting its edge to 
the wind, or partially so. As the wheel has an increasing 
leverage on the governor as it swings farther around, it 
is necessary that there should be an increasing resistance. 
This is accomplished by a travelling-weight, K, on the 
lever R. This weight is suspended at a point above 
the fulcrum by the link V> on which it is adjustable, and 



J 



AMERICAN WINDMILLS: OTHER TYPES. II9 

can be moved up or down, to suit the velocity at which 
the mill is required to run. As the lever R rises, this 
link causes the weight K to travel out on the lever, 
compensating for the positions of the wheel. The turn- 
table is a pivot at the bottom of the bed piece, with a 
collar at the top of the same, both of which are pro- 
tected from the weather, and provided with abundant 
oil cavities. The crank is back connected and coupled 
through a staple to the pump rod, which is hollow, to 
admit of a cable passing down through it, to throw the 
mill out of the wind when it is desired to stop it. The 
staple has a swivel guide at the top, so that it cannot bind 
the crank pin. 

The wheel consists of wrought-iron arms bent on 
edge back on themselves, and clamped on a double-face 
plate. There are twelve of these arms, with malleable 
iron clamps, which slip over the arms, and clamp the rims 
of the wheel. These rims are of hard wood, and sawed 
out, to receive the sails ; the inner and outer rims being 
sawed at different angles, so as to give a screw shape to 
the sails. The frame of the rudder is made of gas-pipe, 
and trussed, and has malleable iron clamps to hold the 
wood cross-pieces which secure the slats. 



The Leffel Windmill. 

The I^efifel Windmill, manufactured by the Springfield 
Machine Company, Springfield, O., is shown in Fig. 40. 
It depends for its regulation on the fact that the centre 



AMERICAN WINDMILLS: OTHER TYPES. 



121 



line of the wind-wheel shaft stands off somewhat from, 
though it is parallel to, the plane of the rudder. The 
wheel of the mill is a distinguishing characteristic. 




Fig. 40. 



The blades, which have a helical curve, are about three 
feet long by two feet wide. They are made of No. 24 
sheet-iron, fastened securely to curved iron ribs, and 
bolted to a double set of one and one-eighth by five- 
sixteenths inch iron arms. 



122 THE WINDMILL AS A PRIME MOVER. 



CHAPTER VIII. 

EXPERIMENTS ON WINDMILLS. 

It is not pleasant to be obliged to make the admis- 
sion, that, for experimental records of the efficiency of 
windmills, we must have recourse to the foreign annals 
of over fifty and over a hundred years ago. With the 
exception of the data of capacity presented in Chap. 
IX., which are the average records of experience rather 
than the results of special experiment, America has con- 
tributed no reliable* data relating to the performance 
and efficiency of windmills. In this chapter we will 
confine ourselves to an account and discussion of the 
experiments of Smeaton and Coulomb. Originally the 
intentioii was to reprint these papers in full ; but the fact 
that their main import can be presented in considerably 
less space, and that their actual value at this time, though 
comparatively of moment, scarcely warrants a complete 
reproduction, has led to the abandonment of the first 
idea. This statement is made with the full knowledge, 
that, as a rule, these experiments are spoken of as if they 
were possessed of no flaw, and also in apparent conflict 

* The author has pointed out elsewhere that the windmill tests at the Penn- 
sylvania Agricultural Exhibition, Philadelphia, 1884, were utterly unreliable, and 
of no value whatever. See American Engineer, vol. 8, July 4, Oct. 17, and Dec. 
26. 1884. 



EXPERIMENTS ON WINDMILLS. I 23 

with the great respect which the author, like many other 
•engineers, has gained for Smeaton and Coulomb, by a 
close perusal of their work in this and many other more 
important departments of engineering. The fact remains, 
however, that the angles recommended by Smeaton as 
the result of his trials, as being "as good as any," cannot, 
in the nature of things, be the most desirable angles, and 
that, in Coulomb's experiments, only the velocity of wind 
was specially recorded, while the total work performed, 
and that lost, were in part calculated, and in part repre- 
sented average annual performances. In how far this is 
the case will appear in our account; and, while it is thus 
the author's aim to warn against the too common blind 
indorsement of the experiments under discussion as 
being final, it is equally his pleasure to commend them 
as the only experimental researches on record worthy of 
study and consideration. 

The hope may here be expressed, that American 
windmill manufacturers may erelong see fit to institute 
such accurate experimental observations of the perform- 
ance and efficiency of windmills as national pride should 
dictate, as scientific accuracy demands, and as the mod- 
ern methods of scientific investigation can readily secure. 

Smeaton s Experiments* — This series of experiments 
with model windmills was instituted by the great English 
engineer John Smeaton, to determine the best shape of 
sail for a given area of surface. Of one set of wind- 
mills experimented upon, the radius was 21 inches, the 
length of cloth 18 inches, breadth 5.6 inches; making an 

* See Philosophical Transactions, 1755 to 1763. 



124 THE WINDMILL AS A PRIME MOVER. 

area of 100.8 square inches for each sail. In the second 
set, there was added to each sail a triangular cloth whose, 
base was equal to one-half the breadth, i.e., 2.8 inches, 
and whose height equalled 18 inches, the sail being 
broadest at the extremity of the radius, or whip. Thus 
the total area was 126 square inches. Number of arms 
of windmills = 4. 

On account of the uncertainty of the wind, the wheel 
was moved, not by allowing or causing the air to move 
against the wheel, but by turning the axis of the wheel 
progressively around in the circumference of a large 
circle, and thus causing the revolution of the wheel by 
its impingement upon the air at rest. The effect was 
then, of course, precisely the same as if wind of a like 
velocity to that with which the air at rest was impinged 
had acted by its impulse upon the wheel. This turning 
of the wheel in the circumference of a large circle was 
effected by giving a circular motion to an upright shaft 
by means of a cord wound on a barrel upon the shaft, 
which cord was operated by the experimenter. To this 
shaft was framed an arm 5 J feet long, at the end of which 
was the seat of the windmill. The power of the wheel 
was measured by a scale pan attached to a fine cord, 
which latter wound about the shaft as it rotated, and thus 
raised the scale and its weights. The scale moved up 
and down in the direction of the upright shaft, and 
received no disturbance from the circular motion. The 
main results of his experiments are given by Smeaton in 
the following table, and the principal deductions there- 
from are expressed in the maxims on p. 126. 



EXPERIMENTS ON WINDMILLS. 



"5 



•J 



§ 

2 
o 

a 
?» 

•J o 

3 ■< 
5 w 
Q s 
g5 

£T 

o < 

25 

W 
2 

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w 

x 

w 

fe« 
o 

c^ 
H 
W 
c/j 



D 
! X 

fa 
O 

H 
Z 

w 

H 
X 

w 



Si 

H H 

2 K 
2 ° 



O 
g 

s 

E 



"5 2 J 
111 

,3 "E °« 







3 


o 


o 




8 

en 


8 


2. 

en 








* 

♦ 


in 


8 <8 

«0 in 


O 


a 



O 


o 


o 


o 


o 


o o 


O 


o 


O 


O 


O 


O 


O 


O 


O O 


O 


O 


O 






O en en m °° 'O a . *0 "+*?*}*: T **. ** 

<d oo oo* e*. eo'et «ooco isacoad in 

I I I 

oooo ooooooooooo 



« * - .2 v 6 
« .2 > 



O ^ O n<o ao oo vo m ro cb «C m (> 

.. I .... I I I .... I 

o oo oo ooooooooo 



158 



•s J j j j j j j jf } jf issss^t 



11 



■ m -*- <0 <0 <0 m a t V)* *n en OO 5> « ©> <0 n tO 

n«t<r<tmm4inv)i0(0 mt^oo is. ts» o m 



J«J 



• o «o « m m n e« 

M if> in m CO | i i »? ►? ~ 

£ << n oo Oi in oo oo 



m is. <«• » c> en ao i*. 
ao ro o» «"> «0 e» n oo | 

o**ddtim*><rt*» 



as e 



«00«QO»nO«nQ005>Mioooo.o»n«0 
•n rn t*. o O *? *? ^ » *? *? *! T *i " °. °. T °- 
is. <d <d is. is. is. od ■«- is. iC oo' oo oo m ei n <o oo 



8 1 5 • a b 

a ^ "a -c .2 3 



n o p» «0 «0 O n n cm» fs. en <o m ■«•■ O en ■*■ •*■ 

"T C*» *0 <0 <« is. <0 9 N N N N <0 N N «6 « <0 >0 



" « C T3 



S . S 4 * . i i 8 8 i 8? 3 8 «? E* * * o S 



H S c 

o < 



ia 



a5 x ^ 

« m oo o p* « m < 
m m m S « en x 



a n « en ci a 






w>e»»nooo«»noenir>ts.o«is.O««'>«ci 

(V>MMM MM MM MMMMM 



•*• m <0 is. oo OO m « m »•■ »n «0 is. oo O 



s 






s 
s 



£ 3 



% \ 

M M 

1 1 



J' 



1 

£ 



1 1 



-= 8 




126 THE WINDMILL AS A PRIME MOVER. 

The column marked "Product" gives the relative 
capacity of the mills. 

In regard to the area of the sails as compared to the 
circular area of the wheel, Smeaton found, that, beyond 
a certain degree, the more the area is crowded with sail, 
the less effect is produced in proportion to the surface. 
By pursuing the experiments still farther than recorded 
in No. 19 of Table VI., it was found by him, that though 
in No. 19 the surface of all the sails together was not 
more than seven-eighths of the circular area containing 
them, yet a further addition rather diminished than in- 
creased the effect ; so that, when the whole cylinder of 
wind is intercepted, it does not then produce the greatest 
effect, for want of proper interstices to escape. 

smeaton's maxims. 

1. The velocity of the windmill sails, whether unloaded, or loaded 
so as to produce a maximum, is nearly as the velocity of the wind ; their 
shape and position being the same. 

2. The load at the maximum is nearly, but somewhat less than, as 
the square of the velocity of the wind ; the shape and position of the sails 
being the same. 

3. The effects of the same sails at a maximum are nearly, but some- 
what less than, as the cubes of the velocity of the wind. 

4. The load of the same sails at the maximum is nearly as the 
squares, and their effects as the cubes of their number of turns in a given 
time. 

5. When the sails are loaded so as to produce a maximum at a 
given velocity of the wind, and the velocity of the wind increases, the 
load remaining the same : first, the increase of effect, when the increase 
of the velocity of the wind is small, will be nearly as the squares of those 



EXPERIMENTS ON WINDMILLS. 1 27 

velocities ; secondly, when the velocity of the wind is double, the effects 
will be nearly as 10 to 27^; but, thirdly, when the velocities compared 
are more than double of that where the given load produces a maxi- 
mum, the effects increase nearly in a simple ratio of the velocity of the 
wind. 

6. If sails are of similar figure and position, the number of turns in 
a given time will be reciprocally as the radius or length of the sail. 

7. The load at a maximum that sails of a similar figure and position 
will overcome at a given distance from the centre of motion, will be as 
the cube of the radius. 

8. The effects of sails of similar figure and position are as the 
square of the radius. 

9. The velocity of the extremity of Dutch sails, as well as of en- 
larged sails, in all their usual positions, when unloaded, or loaded to a 
maximum, is considerably quicker than the velocity of the wind. 

In relation to these maxims, it may be said that their 
exactness is open to all the doubts which any experi- 
ments made on a small scale, and without a commensu- 
rate degree of accuracy, are subject to. Again : they do 
not convey such specific information and exact relations 
of the factors entering the problem as is the character- 
istic demand of the present time. Altogether, the author 
is led to attach Jess importance to the value of Smeaton's 
experiments, for the solution of the efficiency problem of 
the day, than is usually assigned to them. 

Smeaton adds, in a note to his paper — 

" I have found, by several trials in large, the following angles to 
answer as well as any. The radius is supposed to be divided into six 
parts ; and one-sixth, reckoning from the centre, is called 1, the extrem- 
ity being denoted 6. Nos. 1, 2, 3, 4, 5, 6, angle with the axis 72 , 71 , 



128 THE WINDMILL AS A PRIME MOVER. 

72 , 74 , 77J , 8$°. Angle with the plane of motion" jangle df 
weather], " i8°, 19 , 18 (middle), 16 , 12^°, f (extremity)." 

These angles are those quoted in all text-books and 
engineering pocket-books as the best angles of impulse 
and weather, as determined by Smeaton ; but it must be 
stated, in justice to Smeaton, that he does not term them 
the best angles of impulse, but simply says they " answer 
as well as any," possibly any that were in existence at his 
time. Mathematical considerations* conclusively show 
that the angle of impulse depends upon the relative 
velocity of each point of the sail and the wind, the angle 
growing larger as - becomes greater. It will be noticed 
that Smeaton's angles do not fulfil this condition : the 
angle of impulse at No. 2 being less than at No. 1 , while 
the velocity is twice as great ; and the angle at No. 3 
being the same as at No. 1, while the velocity is three 
times as great. Thus an important discrepancy is dis- 
covered, which should not be disregarded in a correct 
and impartial estimate of Smeaton's work. 

Inasmuch as the best angles of impulse are dependent 
upon the relative velocity of the wind and of the mill, and 
as the velocity of the latter is to a great extent depend- 
ent upon the amount of work to be done each revolution, 
the determination of the best angles of impulse is of 
necessity a matter of special study in each particular case. 

Coulomb's Experiments^ are the record of careful 

* See p. 33. 

t Th^orie des Machines Simples, Paris, 1821, par C. A. Coulomb. 



EXPERIMENTS ON WINDMILLS. 1 29 

observations made at Lille, in Flanders, to determine the 
average effects produced by windmills the year around. 
These mills, of which there were more than fifty near 
Lille, were of the Dutch type, and were employed in the 
extraction of oil from rape-seed. The following repre- 
sents the main particulars of these mills : Radius of sail 
= 33 French feet {pied de roi ; i pied de roi = 2?ii 
English feet) ; breadth of sail = 6.2 French feet, 5.2 of 
which consisted of canvas covering framework ; dis- 
tance from axis of shaft to beginning of sail proper = 6 
French feet; angle which element at this point made 
with the axis of the shaft = 6o° ; angle which element at 
the extremity of the sail made with the axis = 78 . In 
regard to these angles, which increased quite regularly 
from 6o° to 7 8°, it is elsewhere shown* that they are those 
of maximum effect ; and, indeed, Coulomb, in speaking of 
these mills, says, that, " by force of trial, the construction 
of these machines has reached a very great degree of 
perfection." The shaft which was inclined from 8° to 15 
to the horizontal, was pierced by seven beams 42 inches 
long, which acted as cams for raising seven stampers 
twice during each revolution of the wheel. Of these 7 
stampers, 5, used for pounding the rape-seed, were of 
oak, 21 feet long by 10 inches square, provided with an 
iron head 55 pounds in weight ; each of the stampers 
weighing 1,020 pounds. The other two stampers, used 
to clasp and slacken the wedges extracting the oil by 

* See p. 43. 



I3O THE WINDMILL AS A PRIME MOVER. 

strong compression, were of the same length, but only 
6.5 inches square, and weighed 500 pounds each. At 
the time of the special observations herein recorded, 
only one of these stampers was used. The velocity of 
the wind was measured by light feathers, which the wind 
carried along. Two men, placed on a small elevation in 
the direction of the wind, and 150 feet from each other,, 
observed the time required by the feathers to pass the 
150 feet. Of course this method involved the possibility 
of a slight error in the matter of record, and presented a 
chance that the velocity of wind recorded differed slightly 
from that with which the wind actually struck the mill. 
The velocity of wind thus obtained was 20.5 French feet 
per second ; the mill making 13 revolutions per minute, the 
four sails having all their canvas spread. The barometric 
pressure is not recorded. The actual mechanical effect 
produced in one minute equalled (1020 x 13 X 10 -f- 50a 
X 13) pounds raised i£ feet, or 1,000 pounds raised 218 
feet per minute. The effect lost by the shock of the 
cams and stampers was computed mathematically by 
Coulomb, and found equal to 1,000 pounds raised i6j- 
feet per minute. The loss of effect by friction (obtained 
experimentally by giving motion to the windmill, while at 
rest, by the application of weights at the extremities of 
the sails) equalled 1,000 pounds raised 18 J feet per min- 
ute. Therefore the total mechanical effect equalled the 
raising of 1,000 pounds (218+ 16J+ i8%=) 2 55 French 
feet per minute. 

The above figures represent the average work of 



EXPERIMENTS ON WINDMILLS. 131 

the windmills described. The velocity of the wind was 
the only item specially obtained by Coulomb. Great as 
is the value of Coulomb's record, it is meet to bear this in 
mind, as well as the following extract from his work : — 

" In these observations, I but followed in silence the work of the 
miller {artiste), and I did not influence any thing in his operation. I 
wished afterwards to have the disposition of the working of the mills, 
so as to vary their action ; thus, I would have procured a series of ex- 
periments to establish the theory of these machines on the basis of a 
great number of cases. But, when the proprietors learned what use I 
wished to make of their machines, I could never induce them to lend 
me the same for a few months' experimental work." 

Such data, the lack of which Coulomb deplored, are 
still missing; but in view of the broader views which 
manufacturers, in general, hold to-day in regard to the 
value of scientific work, and of a correct analysis and 
appreciation of their machines, it is not too hazardous to 
give expression to the belief that it will not be many 
years before such data are at hand. 



I32 THE WINDMILL AS A PRIME MOVER. 



CHAPTER IX. 

THE CAPACITY AND ECONOMY OF THE WINDMILL. 

The Standard of Economy. — The prime mover, 
.which develops and furnishes the desired amount of 
horse-power for the least current money expense, is the 
most economical. It is too often forgotten, that all the 
separate running expenses of obtaining the power should 
be expressed in money values, that these should be 
added, and the sum regarded as the price of the power. 
The smaller the price for reliably furnishing the required 
power (or for performing the required work), the more 
advantageous the use of the prime mover. 

A glaring example of the damage done, and the 
loss of money incurred, by a disregard of this standard 
of economy, is seen in much of the present practice of 
steam engineering. The amount of steam consumed 
per horse-power developed is too often erroneously con- 
sidered the sole test of economy, and the methods of use 
of steam in engines made to conform to, and judged of 
their relative value by, this test. The author has else- 
where* pointed out some of the striking effects which 

* The Most Economical Point of Cut-off in Steam-Engines, by James E. Denton 
and Alfred R. Wolff; Transactions American Society of Mechanical Engineers, 



THE CAPACITY AND ECONOMY OF THE* WINDMILL. 1 33 

the more rational view of economy has on steam-engine 
practice, and especially in the determination of the ratios 
of expansion of steam in cylinders, which will secure the 
most economical working of the engines. 

Even so great an authority as Sir William Thomson,* 
when he originally proposed the use of the windmill for 
storing electrical accumulators, urged, as a difficulty to 
the adoption of the same in its present state of develop- 
ment, that the first cost was too great. For the time 
being, he overlooked the fact, that interest f on capital, 
and not capital itself, is one, and by no means the sole 
item of current expense, by which the economy of prime 
movers should be judged. 

The current expense of any prime mover, or the cost 
of obtaining the horse-power developed per unit of time, 
— which alone should form the basis of a comparison of 
the economy of different prime movers, — consists prin- 



188 1 ; American Engineer, June, July, August, and November, 1881 ; American 
Machinist, Aug. 6, 1881 ; Proceedings Institution of Civil Engineers, London, vol. 
lxviii., session 1881-82, Part II. p. 75, and vol. lxix., session 1881-82, Part III. 
p 44. 

* Presidential address "On the Sources of Energy in Nature Available to 
Man for the Production of Mechanical Effect," delivered before Section A of the 
British Association for the Advancement of Science, 1881. 

t In the same paper, Sir William Thomson, in estimating the cost of utilizing 
the power of the' Niagara Falls for electric lighting, correctly considers the interest 
on first cost in determining the economical aspect of the question. The oversight, 
noted in the text, becomes important and worthy of mention only, inasmuch as any 
statement of so distinguished and justly esteemed an authority as Sir William 
Thomson is apt to be accepted on the basis of authority alone ; and it must be 
added, that the great caution usually displayed by the most eminent living English 
physicist entitles him prima facie to this mark of consideration. 



134 TH E WINDMILL AS A PRIME MOVER. 

cipally of interest, repairs, and depreciation of plant, cost 
of fuel, oil, and attendance. 

There are, of course, in addition, other expenses, like 
insurance, engineers' stores, etc., which will suggest 
themselves ; but these are here considered of too trivial 
import to be taken into account. The comparative 
economy of the windmill and of other prime movers, 
detailed in this chapter, is based on the sum of the 
expenditures enumerated above. 

The Capacity of the Windmill. — To judge of the 
economy of the windmill, it is necessary to be acquainted 
both with the items of current expense of developing the 
power, and with the power developed by various-sized 
mills, when driven by wind of specified average velocity. 
It is to be regretted that there are not in existence such 
serviceable data relating to capacity, obtained by dynamo- 
metrical measurement of the actual horse-power of the 
mill, and by simultaneous anemometrical measurement 
of the actual velocity of wind. With the exception of 
the experiments already referred to,* no direct accurate 
measurement of the horse-power developed has been 
published ; and said results are not complete enough for 
our purpose. 

Fortunately, however, the author is enabled tc pre- 
sent reliable average performances, expressed in pump- 
ing capacity or effect, of various sizes of a standard type 
of American windmill. 

Some eight years ago one of the most prominent 

* See the experiments of Smeaton and Coulomb, pp. 123, 128. 



THE CAPACITY AND ECONOMY OF THE WINDMILL. 1 35 

windmill manufacturers * came to the author with a few 
scattered data of actual performances of his mills, which, 
however, were sufficient, by means of deductions and 
analogy from theoretical principles, to warrant the prep- 
aration of Table VII., given on p. 136. From the quantity 
of water raised to the specified direct elevation, it is, of 
course, an easy matter to calculate the corresponding 
horse-power ; but it should be remembered that there is 
a loss by the friction of the water in the pipes, so that a 
slightly greater horse-power can be relied upon where 
the windmill is used direct for power purposes. Inas- 
much as the present principal application of windmills 
is for pumping, the table of capacity, in the form 
presented, will be found of the greatest use in practice. 

Since the preparation of Table VII., over fifteen hun- 
dred windmills have been sold on its guaranty; and in 
all cases the actual results obtained, both in this countrjj 
and elsewhere, did not vary sufficiently from those pre- 
sented to cause any complaint whatever, — a proof that 
the results as tabulated are correct, or certainly not too 
high. If it be claimed that the horse-power developed 
appears small,f from the stand-point of a (false) preva- 
lent popular opinion, it should be observed, in response, 
that the actual results noted in the table are in close 
agreement with those obtained by theoretical analysis 

* Mr. A. J. Corcoran. For description of the mill, see p. 78. 

t Coulomb, in his experiments with a windmill of four sails seventy feet in 
diameter, breadth of sails six and five-eighths feet, the wind blowing at a velocity 
of fifteen miles per hour, obtained an actual useful result equivalent to about seven- 
horse power. See p. 130. 



136 



THE WINDMILL AS A PRIME MOVER. 



of the impulse of wind upon windmill blades. The 
manufacturer's own observations during the past eight 
years have led him to conclude that they are correct. 
A careful examination of a number of claims of the 
development of greater horse-powers with the same 
velocity of wind, led to the discovery that such claims 
did not rest on a safe basis.. In not a few cases, and 
even in catalogues of foreign windmill manufacturers, 
the nominal horse-power stated far exceeded those in 
Table VII. ; while the actual pumping effect recorded, as 
found in practice, was considerably below that noted in 
the table: showing a lamentable discrepancy, and the 
worthlessness of the claim of a horse-power exceeding 
that theoretically possible. 

TABLE VII. 

SHOWING CAPACITY OF THE WINDMILL. 



1 


2 


3 


4 


6 


6 


7 


8 


9 


10 


11 


12 






-0*1 


j 


Gallons of Water Raised per 


— u 
O 1 


ber of 

Day 

h this 

be Ob- 




Designa- 
tion of 
Mill. 




*o 

| 

3 

1 
& 


Minute to an Elevation of 


o>_ 


Average Nuni 
Hours per 
during whic 
Result will 1 
lained. 


r 25 
feet. 


feet. 


r 75 
feet 


100 
feet. 


150 
feet. 


200 
feet. 


I. 


8^-ft. wheel 


16 


70 to 75 


6.162 


3.016 


_ 


_ 


_ 


_ 


004 


8 


II. 


io-ft. wheel 


16 


60 to 65 


19.179 


9563 


6.638 


4750 


- 


- 


O.X2 


8 


III. 


i2-ft. wheel 


16 


55 to 60 


33.941 


17-952 


11-851 


8.485 


5.680 


- 


0.2I 


8 


IV. 


14-ft. wheel 


16 


50 to 55 


45.139 


22.569 


15-304 


11.246 


7.807 


4.998 


O.28 


8 


v. 


16-ft. wheel 


16 


451050 


64.600 


3I-654 


19.542 


16.150 


9.771 


8.075 


O.4I 


8 


VI. 


18-ft. wheel 


16 


40 to 45 


97.682 


52.165 


32513 


24.421 j 17.485 


12.211 


O.61 


8 


VII. 


20-ft. wheel 


.6 


35 to 40 


124.950' 63.750 


40.800 


31.248 19.284 


15.938 


O.78 


8 


VIII. 


35-ft. wheel 


16 


30 to 35 


212.381 106.964 


71.604 


49725|37.349 


26.741 


x-34 


8 



THE CAPACITY AND ECONOMY OF THE WINDMILL. 1 37 

These windmills are made in regular sizes, as high as 
sixty-foot diameter of wheel ; but the experience with 
the larger class of mills is still too limited at this date to 
enable the presentation of precise data as to their per- 
formance. 

If the wind can be relied upon in exceptional locali- 
ties to average a higher velocity for eight hours a day 
than that stated in the above table, the performance or 
horse-power of the mill will be increased, and can be 
obtained by multiplying the figures in the table by the 
ratio of the cube of the higher average velocity of wind 
to the cube of the velocity above recorded. 

Economy of the Windmill* — The standard of 
economy of prime movers having already been defined, 
it is only necessary to particularize, that in windmills the 
cost of fuel is zero, wind being a free gift of nature, and 
that the attendance required for the leading American 
types of self-regulating windmills amounts only to filling 
the oil-cups three or four times a month, work which 
any one can attend to in a few minutes. If any 
account is to be taken of this service, an allowance of 
fifteen cents a month would really be quite extravagant. 
In the following table such allowance has been made. 
Experience has shown that the repairs and depreciation 
items, jointly, are amply covered by five per cent per an- 

* Note on the Economy of the Windmill as a Prime Mover, by Alfred R. 
Wolff ; Transactions American Society of Mechanical Engineers, 1882 ; Engi- 
neering, Aug. 18, 1882 ; American Engineer, April 22, 1882 ; Journal of the 
Franklin Institute, July, 1882 ; Proceedings Institution of Civil Engineers (Lon 
don), vol. hex., session 1881-82, Part IV. 



138 



THE WINDMILL AS A PRIME MOVER. 



num. Interest is calculated at five per cent per annum. 
The oil used is a very small quantity, — a few gallons per 
year, — and is allowed for in the table according to the 
size of mill. All the items of expense, including both 
interest and repairs, are reduced to the hour by dividing 
the costs per annum by 365 X 8 = 2920 ; the interest, etc., 
for the twenty-four hours being charged to the eight hours 
of actual work. By multiplying the figures in column 6 
by 36s * 8 „ = S84, the first cost of the windmill, in dollars, 

J 100 x 0.05 *> • ' y J 

is obtained. 

TABLE VIII. 

SHOWING ECONOMY OF THE WINDMILL 



1 


2 


8 


4 


5 


6 


7 


8 


9 


10 


11 






1 


5T5 


5-g.g 


Expense of Actual Useful Power 


u 






l& 


§•! 


Developed, 


in Cents, 


per Hour. 


i 






** 3 
B 

«j 

si 



P 


a *=a 








• 3 

u 

■58. 

P 

w 




Designation 
of Mill. 


Average Number of 
per Day during 
this Quantity wi 
Raised. 


For Interest on First 
Cost (First Cost, 
including Cost of 
Windmill, Pump, 
and Tower. 5 per 
Cent per Annum). 


For Repairs and De- 
preciation (5 per 
Cent of First Cost 
per Annum). 


8 

9 

C 

B 

< 

1 


O 

£ 


"3 


I. 


8H-ft. wheel 


370 


0.04 


8 


0.25 


0.25 


0.06 


O.04 


0.60 


15.0 


II. 


10-ft. wheel 


1151 


0.12 


8 


0.30 


0.30 


06 


O.04 


70 


5.8 


III. 


12-ft. wheel 


2036 


0.21 


8 


0.36 


036 


06 


0.04 


0.82 


3-9 


IV. 


14-ft wheel 


2708 


0.28 


8 


0.75 


o.75 


0.06 


O.07 


1.63 


5-8 


V. 


16-ft wheel 


3876 


0.41 


8 


1.15 


1.15 


0.06 


O.07 


2-43 


5-9 


VI. 


18-ft. wheel 


5861 


0.61 


8 


x.35 


1-35 


0.06 


O.07 


2.83 


4.6 


VII. 


20-ft. wheel 


7497 


0.79 


8 


1.70 


1.70 


0.06 


O.IO 


3.56 


4.5 


VIII. 


25-ft. wheel 


"743 


i-34 


8 


3.05 


2.05 


0.06 


O.IO 


4.26 


3.2 



The number of gallons pumped by the thirty-foot and 
thirty-five foot mills and larger sizes, and the economy 
of the mills, are not stated in the above table ; for the 



THE CAPACITY AND ECONOMY OF THE WINDMILL. 1 39 

number of larger mills in operation is not sufficient to 
insure authentic precision of the results obtained. The 
performance of the thirty-foot mill, as far as observed, 
seems to gravitate to a pumping capacity equivalent to 
24-horse power, and to an expense of 2.5 cents per 
horse-power per hour. 

The Economy of Steam- Pumps. — In order to ascer- 
tain the relative value of the windmill, its economy 
must be compared with that of other prime movers. 
Accordingly, the author has taken pains to secure from 
the more prominent manufacturers actual data of cost, 
durability, running-expenses, and the like, of the several 
types of steam-pumps of same actual pumping capacity 
as the sizes of windmills mentioned in Table VIII. On 
these data, as a basis, he has prepared Table IX., show- 
ing the economy of steam-pumps, being careful that the 
data selected, and the results obtained, should represent 
the best rather than average practice. 

Relative Economy of the Windmill and Steam-Pump. 
— By comparison of the figures in Column 1 1 of Table 
VIII. and in Column 23 of Table IX., it appears, that, 
even presuming the steam-pump to require no extra 
boiler capacity, and no attendance whatever (or that no 
extra expense is attached to extra attendance and boiler 
capacity), the windmill is by far the most economical 
prime mover. Averaging the several results, its economy 
may be said to be about 1.5 times that of the steam- 
pump when no charge is made for attendance and boiler 
capacity for the latter prime mover. 



140 



THE WINDMILL AS A PRIME MOVER, 



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THE CAPACITY AND ECONOMY OF THE WINDMILL. 141 





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142 THE WINDMILL AS A PRIME MOVER. 

As a fact, however, steam-pumps do require extra 
boiler capacity, and some attendance. 

A comparison of Column 1 1 of Table VIII. and of 
Column 24 of Table IX. shows, that, allowing for an 
independent steam-boiler, but for no attendance for the 
steam-pump, the economy of the windmill averages about 
1.75 times that of the steam-pump. 

A comparison of Column 1 1 of Table VIII. and of 
Column 34 of Table IX. shows that the economy of the 
windmill averages about 2.25 times that of the steam- 
pump, when there is included for the latter a charge for 
boiler capacity, and for the services of one-tenth of the 
time of one man. Of course, the exact relative economy 
of the windmill and steam-pump can be obtained for 
each special desired pumping effect by dividing the. cor- 
responding figure in Column 23 to Column 34 of Table 
IX., respectively, as the case may be, by the correspond- 
ing figure in Column 1 1 of Table VIII. 

It should be remembered that the tankage required 
by a windmill should be equivalent to two, or better 
three days' average daily consumption of water, which 
is larger than necessary to meet the demands when a 
steam-pump is used. But the extra cost involved is not 
sufficient to change the standing of the economy of the 
windmill as compared to that of the steam-pump, though 
its tendency is to decrease its ratio of superiority. The 
question of cost of tank has not entered the above 
comparison ; since the tankage required is to a great 
extent a matter of individual discretion, and dependent, 



THE CAPACITY AND ECONOMY OF THE WINDMILL. 1 43 

too, on ever-varying local conditions and considera- 
tions. 

It is, however, an easy matter, if desired, to include it 
in a comparison of the economy of the two prime movers 
in any special case. All that is necessary is, to divide the 
first cost, in dollars, of tank required for given pumping 
effect of steam-pump, by 584 ; and the figure thus ob- 
tained should be added respectively to the figures in 
Columns 11 to 22, Table IX., and the corresponding 
figure in Column 3, divided by the respective sums. 
Thus will be obtained " the expense per horse-power, in 
cents per hour," denoted respectively by Columns 23 
to 34 for the special conditions stated, inclusive of tank- 
age required. 

Similarly, dividing the first cost, in dollars, of tank 
required for given pumping effect of windmill, by 584, the 
figure thus obtained should be added to Column 10 of 
Table VIII., and the corresponding figure in Column 4 
be divided by the sum: the result will be the " expense 
per horse-power, in cents per hour," for the windmill, 
inclusive of tankage required. 

The ratio of the figures thus obtained for the wind- 
mill and steam-pump will define the relative economy of 
the two prime movers, the necessary tankage for each 
being included in the comparison. 

Relative Economy of the Windmill and Ericssons 
Hot-air Engine. — The following table, based on data 
of cost, consumption of fuel, and the like, published by 
the manufacturers, has been prepared on the same prin- 



144 



THE WINDMILL AS A PRIME MOVER. 



ciples and advantageous footing characterizing the table 
of " Economy of Steam-Pumps." 

TABLE X. 

SHOWING ECONOMY OF ERICSSON'S HOT-AIR ENGINE. 



1 


2 


8 


4 


5 


6 


7 


8 


9 




Gallons of 

Water 

Raised 50 

Feet per 

Hour. 


Equivalent 
Actual 
Useful 
Horse- 
Power De- 
veloped. 


Expbnsb of Actual Useful Power Developed, 
in Cents per Hour. 


Expense 
per Horse- 
Power, in 
Cents per 
Hour. 


For Interest 
5* of First 
Cost. 


For Repairs 
and Depre- 
ciation, 5$ of 
First Cost. 


For Coal, $5 
per Ton of 
2,000 Lbs. 


1 


1 


I. 
II. 
III. 

IV. 


900 
35o 
800 
1600 


0.042 
0.074 
0.169 
o.337 


*o-34 
*o.43 
♦0.57 
*o.86 


o.34 
0.43 

0.57 
0.86 


0.63 
0.83 
x.50 
3.00 


0.05 
0.05 
0.06 
o.zo 


x.36 

1-74 
3.70 
4.82 


3238 
23-51 
15.98 
14.30 



A comparison of Column n of Table VIII. and of 
Column 9 of Table X. reveals the fact, that the economy 
of the windmill averages about three times that of the 
Ericsson hot-air engine, when no charge for attendance 
is made for the latter. Where gas is used, the cost for 
fuel is somewhat greater than that above recorded ; but 
the attendance then practically costs nothing. 

Relative Economy of the Windmill and the Gas-En- 
gine. — A gas-engine developing 1.34 actual useful horse- 
power, a performance equivalent to that of the 2 5 -foot 
windmill raising 12,743 gallons of water 25 feet per 

* Multiplying this figure by 584 gives first cost of prime mover in dollars. 



THE CAPACITY AND ECONOMY OF THE WINDMILL. 145 

hour, includes in its operation the following minimum 
expenses : — 

For interest, 5 % on first cost 0.80* cent per hour. 

For repairs and depreciation, 5 % on first cost, 0.80 

For oil 0.40 

For gas -. 8.00 cents 



a K a 
u <( a 



Total 10.00 cents per hour. 

Expense of gas-engine per horse-power per hour, 7.5 cents. 

A comparison of this figure with 3.2 of Column 1 1 
of Table VIII. shows, that, even making no allowance 
for attendance in the running of the gas-engine, the 
windmill is more than 2.25 times as economical as a 
prime mover. 

The comparison instituted in this chapter clearly and 
conclusively proves that at the present time windmills 
are the most economical prime movers for the purposes 
outlined in the Introduction of this work, and for 
powers and pumping-effects ranging from zero to 2.4- 
horse power. The superior economy still maintains, for 
an average pumping-effect equivalent to eight-horse 
power, the highest power developed for an average of 
eight hours per day by the largest-sized windmills de- 
signed in America. The usual range is from ^ to 
4 horse power, the latter being developed by a mill of 
about 40-foot diameter of wheel. 

* Multiplying this figure by 584 gives first cost of prime mover in dollars. 



14© THE WINDMILL AS A PRIME MOVER. 



CHAPTER X. 

USEFUL DATA IN CONNECTION WITH WINDMILL PRACTICE. 

In this chapter it is intended to supply some addi- 
tional formulae, rules, tables, and facts, which may prove 
convenient in the practical application of windmills, more 
especially for pumping-purposes. 

Allowance for Friction of Water in Pipes. 

The work required to overcome the friction of the 
water in its passage through the pipes must be allowed 
for in determining the proper size of windmill to be pro- 
vided. The readiest way to express this friction is in 
terms of the head of water required to overcome it. 
Thus, if a given quantity of water per minute is to be 
raised vertically 50 feet, but has to travel several hundred 
feet through a given-sized pipe in the process of raising, 
the power required will have to equal the raising of the 
same quantity of water per minute, say 54, or 56, or 60 
feet, as the case may be. The extra head can be found 
-approximately by the use of the following data, adapted 
for the purpose from Weisbach's " Mechanics," vol. 2, 
Coxe's edition, p. 868, et seq. ; — 



USEFUL DATA REGARDING WINDMILL PRACTICE. 



H7 



The extra head in feet equals 

, _ 0.1865/ x v x v v / 
d x/ ' 

in which / = length of pipe in feet, 

d = internal diameter of pipe in inches, 

„. — l8 3-34 x Q 



(I) 



u 


<tx d 


y 


V 


Q = cubic feet of water raised per second, 


d = diameter of 


pipe 


in 


inches, and 


/= 








0.0686 when v 


= 


O.IO, 


0.0527 


« « 


= 


0.20, 


0.0457 


tt it 


= 


0.30, 


0.0415 


it u 


= 


0.40, 


0.0387 


ti it 


= 


0.50, 


0.0365 


u a 


= 


0.60, 


0.0349 


n tt 


= 


0.70, 


0.0336 


tt tt 


= 


0.80, 


0.0325 


tt tt 


= 


0.90, 


0.0315 


tt tt 


= 


1. 00, 


0.0297 


tt tt 


= 


i.25> 


0.0284 


tt tt 


== 


i-5°> 


0.0265 


tt tt 


= 


2.00, 


0.0243 


tt tt 


= 


3.00, 


0.0230 


tt tt 


= 


4.00, 


0.0214 


tt tt 


= 


6.00, 


0.0205 


tt tt 


= 


8.00, 


0.0193 


tt tt 
tt tt 


= 


12.00, 



(II.) 



An example will best show the use of these data. 
Let it be required to raise 125 cubic feet of water per 
hour 25 feet, forcing the water through 500 feet of 



I48 THE WINDMILL AS A PRIME MOVER. 

2 -inch pipe ; how many feet direct vertical rise will this 
be equivalent to, the difference being due to friction of 
water in the pipes? 

125 cubic feet per hour = ^-— cubic feet per second; 

60 x 60 

or, by equation (II.), 

183-34 x 125 
v = * °^ ^ = 1.59, 

3600 X 2 X 2 

for v= 1.59, f= about 0.028. Therefore, by equation 

(i.). 

0.1865 * 5°° * r «59 x l -S9 X 0-028 
* = = 3-3 ; 

or, the power required would be the same as to raise the 
125 cubic feet of water 25 + 3.3 = 28.3 feet direct ver- 
tical height. 

[A cubic foot of water weighs about 62.4 pounds. A 
gallon of water measures 231 cubic inches, or 0.13368 
cubic feet, and weighs 8.34 pounds. One cubic foot 
contains 7.48 gallons of water.] 

Substitution in equations (II.) and (I.) gives values 
in close accord with the following table, prepared by Mr. 
George A. Ellis, C.E. Mr. Ellis's table is, however, ex- 
pressed in pounds pressure per square inch. By multi- 
plying the figures in the columns headed " Sizes of Pipes" 
by 2, the approximate head of water, in feet, correspond- 
ing to friction, will be found for each 100 feet of length. 

To obtain the approximate head, in feet, corresponding 
to loss by friction, for any other length of pipe, multiply 



USEFUL DATA REGARDING WINDMILL PRACTICE. 149 



the figures in Mr. Ellis's table by twice that length, and 
divide by ioo. 

TABLE XL 

FRICTION OF WATER IN PIPES. 

Friction Loss, in Pounds Pressure per Square Inch, for each too Feet of Length in 
Different Size Clean Iron Pipes Discharging given Quantities of Water per 
Minute (G. A. Ellis * C.E.) 





Sizes of Pipes: Inside Diameter. 


e 

hi 


B 


c 


c 


c 

M 






a 


c 

NO 


C 
00 


c 




s 

CI 


c 


NO 


d 
00 


5 
10 

15 
20 
»5 
30 
35 
40 
45 
50 
75 
zoo 

"5 

150 

*75 

200 

950 

300 

35o 

400 

450 

500 

750 

1000 

1250 

1500 

1750 

2000 

3250 

2500 

3000 

3500 

4000 

4500 

5000 


3-3 
13.0 
28.7 
50.4 
78.0 


O.84 
3.16 
6.98 
I2.3O 
I9.OO 
27.50 

37-oo 
48.00 


0.31 
1.05 
2.38 
4.07 
6.40 

9-i5 
12.40 
16.10 
20.20 
24.90 
56.10 


O.X2 
O.47 
O.97 

1.66 
2.62 

3-75 
5-05 
6.52 
8.15 
10.00 
22.40 
39.00 


O.X2 
O.42 
O.91 
I.60 
2.44 

5-32 

9.46 
14.90 

21.20 
28.10 
37-50 


0.2Z 

0.8l 
I.80 

3 20 
4.89 
7.00 
9.46 
12.47 
19.66 
28.06 


O.ZO 

O.35 
O.74 

x-3i 

1.99 
2.85 

3.85 

5.02 
7.76 

11.20 
15.20 

19.50 

25.00 
30.80 


0.09 

0.33 

0.69 

z.22 
1.89 
2.66 
3.65 
4-73 
6.01 

7-43 


0.05 
o.xo 

0.17 

0.26 

0.37 
0.50 
0.65 
0.81 
0.96 

2.21 
3.88 


0.07 
0.09 

O.Z2 
O.16 
0.20 
O.25 

0.53 
O.94 
I.46 
2.09 


0.03 
0.04 
05 
0.06 
0.07 
0.09 
0.18 
0.32 

0.49 

0.70 

0.95 
1.23 


o.oz 

0.02 

0.03 
0.04 
0.08 
0.13 

0.20 
0.29 
0.38 
0.49 
0.63 

0.77 

I. II 


017 
0.062 

0.135 
0.234 

0.362 

0.515 
0.697 

0.910 


O.OO9 

O.O36 

O.O7I 

O.I23 

O.I88 
O.267 
O.365 
0.472 
0.593 
O.73O 


0.005 

0.02Q 

O.O40 

O.O7I 

O.IO7 
O.I50 
O.204 
O.263 
0.333 
O.408 



* Fire Streams and Hydraulics, p. 38. 



i5o 



THE WINDMILL AS A PRIME MOVER. 



Thus, let it be required to raise 5,000 gallons of water 
per minute through 600 feet of 16-inch pipe. We note 
in Table XL the figure 0.730; by multiplying this by 
twice 600, or by 1,200, and dividing by 100, we obtain 
0730 x I20 ° = 8.76, which represents the vertical rise of 
water that the loss by friction is equal to. Therefore, if 
the 5,000 gallons of water were to be raised 50 feet per 
minute, being forced through 600 feet length of 16-inch 
pipe, the power required would be the same as to raise 
5,000 gallons of water per minute a direct vertical height 
of 58.76 feet. By making the substitution as here noted 
in Table XL, the results will accord quite closely with 
those obtained by direct calculation from equations (I.) 
and (II.). 



TABLE XII. 



SHOWING CO-EFFICIENT OF FRICTION IN AXLES. 
(From Molesworth's " Pocket-Book of Engineering Formulae.") 



Axle. 


Bearing. 


Dry. 


Greasy 

and 
Wetted. 


Ordinary 
Lubrica- 
tion. 


Lubricated 
Continu- 
ously. 


Lard and 
Plumbago. 


Fatty 
Matter. 


Bell-metal . . 


Bell-metal . 


- 


. 


0.097 


- 


_ 


. 


Cast-iron . . 


a 


- 


- 


- 


0.049 


- 


- 


Wrought-iron , 


Cast-iron . . 


0.25 


0.19 


0.070 


0.050 


0.09 


- 


" 


" 


- 


- 


0.070 


0.050 


- 


- 


Cast-iron . . 


Bell-metal 


, 


0.13 


0.070 


0.050 


- 


0.14 


u 


Lignum-vitae, 


0.19 


0.16 


0.070 


0.050 


0.06 


0.16 


Wrought-iron, 


« u 


0.19 


- 


0.120 


- 


- 


- 


Cast-iron . . 


Cast-iron . . 


0.18 


- 


O.IOO 


0.090 


- 


0.X4 


Lignum-vitae . 


u 


- 


- 


O.ZZO 


- 


- 


0.15 


u tt 


Lignum-vitae, 


- 


" 


•" 


0.070 


" 


• 



USEFUL DATA REGARDING WINDMILL PRACTICE. 



151 



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0.272 
0.425 
0.612 

0.833 

1.088 

1.700 

2.448 

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4-352 

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6.800 

8.228 

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13.328 

17.408 

22.032 

27.200 

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61.200 

88.128 

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152 



THE WINDMILL AS A PRIME MOVER. 



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W 

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ia-foot 
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14-foot 
wheel. 


11 


II 


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A.* 


25-foot 

wheel. 

30-foot 
wheel. 



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9* 



USEFUL DATA REGARDING WINDMILL PRACTICE. 1 53 



TABLE XV. 

GIVING THE NUMBER OF SQUARE FEET AND ACRES THAT A FIRST- 
CLASS WINDMILL CAN IRRIGATE ONE INCH IN EIGHT HOURS, 
RAISING THE WATER 10 FEET, 15 FEET, AND 25 FEET RESPEC- 
TIVELY, AS BASED UPON ACTUAL RESULTS OF PRACTICE. 







10 Feet. 


15 Feet. 


26 Feet. 


Size 


of Windmill. 












Square Feet. 


Acres. 


Square Feet. 


Acres. 


Square Feet. 


Acres. 


8^-foot diameter of wheel, 


1x736.34 


0.269 


7824.74 


0.180 


4744-74 


0.X09 


xo " 


« « 


37x61.74 


0.853 


24774-75 


0.569 


14767.83 


0.339 


13 " 


tt tt 


66765.16 


x-533 


44509-85 


X.OS3 


36x34.57 


0.600 


14 " 


tt tt 


85983.05 


1-974 


57321. 1 1 


X.316 


3475703 


0.798 


x6 " 


tt tt 


1 20106. 14 


2.757 


80070.76 


I.838 


49743.00 


x.142 


18 " 


tt tt 


192446.10 


4.418 


123164.58 


2.827 


752x5.14 


x.737 


30 " 


tt tt 


23839508 


5-473 


158930.31 


3.649 


96211.50 


3.309 


35 " 


It It 


4x0038.09 


9.413 


373359a4 


6.275 


"63533.37 


3-754 


30 " 


tt tt 


83x686.24 


19.093 


561197.56 


12.883 


331753.96 


7.616 



For two inches irrigation in eight hours, divide the figures in above table by 3, for three inches 
by 3, etc. Eight hours represents the average running-time of the mills for irrigation purposes in a day 
of twenty-four hours. 



TABLE XVI. 

SHOWING CAPACITY OF CISTERNS AND TANKS, IN GALLONS, FOR 
EACH TWELVE INCHES IN DEPTH. 



Diameter in 
Feet. 


Gallons. 


Diameter in 
Feet. 


Gallons. 


Diameter in 
Feet 


Gallons. 


1.0 


5.87 


6.5 


348.23 


xx.o 


7x0.90 


2.0 


23.50 


7.0 


387.88 


11.5 


77705 


a-5 


36.72 


7-5 


33048 


X3.0 


846.03 


3.0 


52.88 


8.0 


376.00 


I3.0 


992.9* 


3.5 


71.97 


8.5 


424.48 


I40 


"51-54 


4.0 


9400 


9.0 


475-89 


X5.O 


1331.93 


4.5 


118.87 


9-5 


530.24 


20.0 


3350.08 


5.0 


146.88 


10.0 


587.52 


25.O 


3673.00 


5.5 


177.73 


X0.5 


64774 


30.0 


5287.68 


6.0 


311.51 











For any other depth, multiply the figures in the table by depth, in inches, divided by 13. 



154 



THE WINDMILL AS A PRIME MOVER. 



TABLE XVII. 

SHOWING DIMENSIONS, WEIGHT, ETC., OF WROUGHT-IRON WELDED 
PIPE OF DIFFERENT DIAMETERS. 



Inside 
Diam- 
eter. 


Outside 
Diam- 
eter. 


External 
Circum- 
ference. 


Length 
of Pipe 
perSq. 
Foot of 
Outside 
Surface. 


Internal 
Area. 


External 
Area. 


Length 
of Pipe 
contain- 
ing One 
Cubic 
Foot. 


Weight 

per 
Foot of 
Length. 


No. of 
Threads 
per Inch 
of Screw. 


Contents 
in Gal- 
lons per 
Foot. 


Weight 
ofWatei 

per 
Foot of 
Length. 


in. 


inches. 


inches. 


feet. 


sq. in. 


sq. in. 


feet. 


lbs. 






lbs. 


H 


0.40 


x.272 


9-440 


0.0x2 


0.129 


2500.00 


a 24 


27 


0.0006 


0.005 


X 


o.54 


1.696 


7075 


0.049 


0.229 


1385.00 


0.42 


18 


0.0026 


0.021 


n 


0.67 


2.X2X 


5057 


O.IXO 


0.358 


751.50 


0.56 


«4 


0.0057 


0047 


% 


0.84 


2.652 


4-502 


O.X96 


0-554 


472.40 


0.84 


14 


0.0102 


0.085 


y* 


1.05 


3*299 


3*637 


0.441 


0.866 


270.00 


X.X2 


"J* 


0.0230 


0.190 


I 


1.31 


4.134 


2.903 


0.785 


x-357 


166.90 


1.67 


"J* 


0.0408 


0.349 


xK 


x.66 


5.2x5 


2.301 


1.227 


3-164 


96.25 


2.25 


»H 


0.0638 


0527 


*% 


x.90 


5969 


3.0x0 


X.767 


2.835 


70.65 


2.69 


«% 


0.09x8 


0.760 


2 


2.37 


7.461 


i.6ix 


3.141 


4-430 


42.36 


3.66 


8 


0.1632 


x.356 


*% 


2.87 


9.032 


1.328 


4.908 


6.491 


30.11 


5-77 


8 


0.2550 


2. 116 


3 


350 


10.996 


1 .091 


7.068 


9.621 


19.49 


754 


8 


0.3673 


3049 


35* 


4.00 


12.566 


0.955 


9.621 


12.566 


14-56 


9.05 


8 


0.4998 


4.155 


4 


4.50 


14.137 


0.849 


12.566 


15904 


11.31 


10.72 


8 


0.6528 


5-405 


4H 


5.00 


15.708 


0.765 


15904 


19-635 


9.03 


12.49 


8 


0.8263 


6.851 


5 


5.56 


17.475 


0.629 


19-635 


24.299 


7.20 


14.56 


8 


1.0200 


8.500 


6 


6.62 


20.8x3 


0.577 


28.274 


34.471 


4.98 


18.76 


8 


1.4690 


12.312 


7 


7.62 


23-954 


0.505 


38.484 


45663 


3-72 


2341 


8 


1.9990 


16.662 


8 


8.62 


27.096 


o.444 


50.265 


58.426 


2.88 


28.34 


8 


2.6110 


21.750 


9 


9.68 


30.433 


0.394 


63.617 


73715 


2.26 


34.67 


8 


3.3000 


27.500 


xo 


10.75 


33772 


o.355 


78.540 


90.792 


1.80 


40.64 


8 


4.0810 


34.000 



x inch and below are butt-welded, and proved to 300 pounds per square inch hydraulic pressure. 
x# inches and above are lap-welded, and proved to 500 pounds per square inch hydraulic pressure. 



To find the area of a circle in square inches, multiply 
the diameter, in inches, by itself, and by 0.7854. To 
find the circumference of a circle in inches, multiply the 
diameter in inches by 3.1416. 



INDEX. 



PAGE 

Accumulators, electrical, and wind- 
mills 4 

Acres, number of, irrigated by wind- 
mills 153 

Adams Windmill, description of . . 101 

Air, compression and storage of, by 
windmills 4 

Air, loss of pressure by friction of 
particles of 10 

Air-engine, relative economy of wind- 
mill and 143 

Althouse Windmill, description of . 97 

America, extent of manufacture of 
windmills in 2 

America, extent of use of windmills 

in 2 

America, movement of wind in . . 7 

American experiments on wind- 
mills . . 122 

American windmills, classification of 
types of 75 

American windmills compared to 

European 73 

American windmills, durability of va- 
rious types of 76 

Angles, best, for ventilators ... 37 
best, of impulse and weather . . 33 
Smeaton's 128 

Appreciation of the windmill ... 1 

Archibald's formula for wind velo- 
city 22 

Area, best ratio of sail to circular 
area of wheel • . 126 



PAGE 

Area of circle 1 54 

Average movement and velocity of 

wind 6 

Average velocity of wind driving 

windmill 8 

Average work of windmills .... 3 

Baker, B., on high wind pressures . 25 

Barometric pressure, its effect on 
wind pressure 11 

Batteries, storage, and windmills . . 4 

Bender, C. B., on high wind pressures, 22 

Best angles for ventilators . . . . 37 
of impulse and weather . . . . 33 
of impulse and weather (Smea- 
ton's) 128 

Best ratio of sail to circular area of 
wheel 126 

Blades, analysis of impulse of wind 
on windmill (Rankine's) ... 30 

Blades, analysis of impulse of wind 
on windmill (theoretical) ... 28 

Blades, analysis of impulse of wind 
on windmill (Weisbach's) . . 31 

Buchanan Windmill, description of . 104 

Calms, and the use of windmills . . 3 
Capacity and economy of windmill . 132 
Capacity of cisterns and tanks . . 153 

of windmill 134 

of windmill pumps of different 
diameters and strokes . . . .151 
Centrifugal-governor windmills . . 89 
*55 



156 



INDEX. 



PACE 

Champion Windmill, description of 

geared mill in 

Champion Windmill, description of 

pumping-mill 109 

Character of wind, and the use of 

windmills 3 

Circle, circumference and area of .154 
Class and proper diameter of pumps, 152 
Classification of European windmills, 52 
of types of American windmills . 75 
Comparison of American and Euro- 
pean windmills 73? 74 

Comparison of side-vane and centrif- 
ugal-governor mills 77 

Corcoran Windmill, description of . 78 
for railway water supply .... 82 

for water supply 79 

geared mill for power purposes . 82 

tower, 82 

Corn, windmills used for shelling . 4 
Coulomb's description of mills ex- 
perimented upon by himself . .129 
Coulomb's discussion of experi- 
ments ... 131 

Coulomb's experiments on wind- 
mills 42, 128 

Coulomb's results of experiments . 130 
Cubic contents of a gallon .... 148 
Cubic foot of water, weight of . . 148 
Cubitt's method of governing . . . 71 
of reefing windmill sails .... 70 

of turning dome 64 

Current expense of Halladay Wind- 
mill 94 

Data, useful, in connection with wind- 
mill practice 146 

Definition of wind 5 

Description of Adams Windmill . . 101 
of Althouse Windmill .... 97 
of Buchanan Windmill . . . .104 
of Champion Windmill .... 109 
of Corcoran Windmill .... 78 
of Eclipse Windmill ..... 87 
of Halladay Windmill .... 89 
of horizontal windmills .... 54 

of Leffel Windmill 119 

of Regulator Windmill . . . . 11 1 



PAGE 

Description of Stover Windmill . . 106 

of Strong Windmill 115 

of vertical windmills 55 

of windmill sails 58 

of windmills experimented upon 

by Coulomb 129 

Description of Woodmanse Wind- 
mill 106 

Details of Smeaton's experiments . 123 
Diagram showing best angles of 

impulse and weather .... 36 
Diameter, proper, of pumps . . .151 
Dimensions, weight, etc., of wrought- 

iron pipes . . . . 1 . . . 154 
Disadvantages of horizontal wind- 
mills 54 

Discussion of Coulomb's experi- 
ments 131 

Discussion of Smeaton's conclusions, 127 
Dome, Cubitt's method of turning . 64 
Durability of American windmills . 78 

Dutch or tower mills 63 

Dwellings, domestic, and the use of 
windmills 4 

Early history of windmills .... 45 

Eclipse Windmill 87 

Economical motors, windmills • . 1 

windmills the most 3, 145 

Economy and capacity of the wind- 
mill 132 

Economy of windmill as affected by 

tankage 142 

Economy of windmill compared to 

Ericsson's hot-air engine . . .143 
Economy of windmill compared to 

gas-engine 144 

Economy of windmill compared to 

steam-pump ....<.. 139 
Economy of windmill, standard of .132 
Effect, loss of, by friction of shaft . 41 
of barometric on wind pressures . 1 1 
of temperature on wind pressures, 8 
of wind on plane surfaces ... 8 
theoretical mechanical, of wind- 
mill sail 33 

Effect, theoretical mechanical, of 

windmill with plane sails ... 40 



INDEX. 



157 



PAGB 

Effect, theoretical mechanical, of 
windmill with shape of sail for 
maximum effect 37 

Efficiency of windmills 122 

Electrical accumulators and the use 
of windmills 4 

Employment, special, of windmills . 4 

Establishments, manufacturing, and 
the use of windmills .... 4 

European windmills 52 

description of sails 58 

European windmill governors ... 67 

Expense, current, of Halladay Wind- 
mill 94 

Expense, current, the basis of com- 
parison of prime movers . . . 133 

Experiments on windmills, Smea- 
ton's 123 

Experiments on windmills, Cou- 
lomb's 42, 128 

Extent of manufacture of windmills 
in America 2 

Extent of use of windmills in Amer- 
ica 2 

Extent of use of windmills in the 
world 1 

Farms and the use of windmills . . 4 
Feed, cutting, and the use of wind- 
mills 4 

Field on relation of velocity and 

pressure of wind 18 

Filler's windmill 97 

Fresnel on high wind pressures . . 23 
Friction of axles, loss of effect by . 41 
table showing co-efficient of . . .150 
Friction of particles of air, loss of 

pressure of wind by 10 

Friction of water in pipes, allowance 

for 146 

Friction of water in pipes, table 

showing loss by 149 

■Gallon, cubic contents of . . . .148 
Gas-engine, relative economy of wind- 
mill and 144 

Gaudard on high wind pressures in 
England and France .... 23 



PAGE 

Gaudard on relation of velocity and 

pressure of wind ...... 18 

German or post windmills .... 60 

Hagen on relation of velocity and 

pressure of wind 20 

Halladay Windmill, current expense 

of 94 

Halladay Windmill, description of . 89 

fan of 93 

for power purposes 94 

for railway water supply .... 94 

in Germany 97 

iron-work of 92 

Hartnup on high wind pressures in 

Great Britain 25 

Hawksley on relation of velocity and 

pressure of wind 17 

Height of observation and velocity 

of wind 21 

Height of observation and velocity 

of wind, Archibald on .... 22 
Height of observation and velocity 

of wind, Stevenson on . . . . 21 

History, early, of windmills ... 45 

Horizontal windmills 52 

compared to vertical 55 

description of '52 

disadvantages of 54 

Hot-air engine, economy of Erics- 
son's 144 

Hot-air engine, Ericsson's, relative 

economy of windmill and . . . 143 
Hours, number of, windmills run per 

day 8 

Impulse, best angles of 33 

Smeaton's angles of 128 

Impulse of wind on windmill blades, 28 

Rankine's analysis of 30 

theoretical analysis of 28 

Weisbach's analysis of .... 31 

Irrigation by windmills, table show- 
ing capacity 153 

Leffel Windmill 119 

Loss, by friction, of water in pipes . 149 
of effect by friction of the shaft . 41 



i 5 8 



INDEX. 



Loss of pressure of wind by friction 
of particles of air 10 

Manufacturing establishments and 

the use of windmills .... 4 

Maxims, Smeaton's 126 

Mechanical effect of windmill sail . 33 
of windmill of shape of sail for 

maximum effect 37 

Mechanical effect of windmill with 

plane sails 40 

Meikle's method of reefing windmill 

sails 69 

Movement of wind, average ... 6. 

in America 7 

Pipes, weight of wrought-iron . . .154 
Pole on relation between pressure 

and velocity of wind .... 19 
Post or German windmills .... 60 
Power, windmills for storing ... 4 
Practice, useful data in connection 

with windmill 146 

Pressure, effect of barometric on 

wind 11 

Pressure, high wind 22 

high wind, C. Shaler Smith on . . 24 
high wind, Gaudard on .... 23 
high wind, Hartnup on .... 25 
loss of, by friction of particles of 

air 10 

Pressure, relation between actual and 

theoretical wind 10 

Pressure, relation between velocity 

of wind and 9,12,13 

Pressure, relation between velocity 

of wind and, Gaudard on . . . 18 
Pressure, relation between velocity 

of wind and, Hagen on ... 20 
Pressure, relation between velocity 

of wind and, Hawksley on . . 17 
Pressure, relation between velocity 

of wind and, Rankine on . . . 16 
Pressure, relation between velocity 

of wind and, Weisbach on . . 15 
Pressure, Smeaton's table of wind . 14 
Pumping water and the use of wind- 
mills 1, 4 



PAG* 

Pumps, capacity of windmill . . .151 

class and diameter of windmill . .152 

economy of steam .... 1 39-1 41 

relative economy of windmill and 

steam 139 

Raising sand, windmills for . . . 4 
Rankine on impulse of fluid on vanes, 30 
Rankine on relation of velocity and 

pressure of wind 16 

Ratio, best, of area of sail to circular 

area of wheel 126 

Reefing windmill sails, Cubitt's 

method of 7a 

Reefing windmill sails, Meikle's 

method of 69 

Regulator Windmill 11 1 

Relation between pressure and velo- 
city of wind . . . 8, 9, 12, 13, 15 
Relation between theoretical and 

actual wind pressures .... 10 
Relative economy of windmill and 

Ericsson's hot-air engine . . . 143 
Relative economy of windmill and 

gas-engine 144 

Relative economy of windmill and 

steam-pump 139 

Results of Smeaton's experiments . 125 
of Coulomb's experiments . . .130 

Sails, Cubitt's method of reefing 

windmill 70 

Sails, description of European wind- 
mill 58 

Sails, Meikle's method of reefing 

windmill 69 

Sails, plane, mechanical effect of 
windmill with 40 

Sails, shape of, for maximum effect . 34 
shape of, for maximum effect, 
mechanical effect of 37 

Scott on high wind pressures ... 22 

Shaft, co-efficient of friction of . .150 
loss of effect by friction of ... 41 

Side-vane governor compared to cen- 
trifugal-governor windmills . . 77 

Smeaton's experiments, results and 
discussion of 123 



INDEX. 



IS9 



PAGE 

Smith, C. Shaler, on high wind press- 
ures 24 

Specific uses of windmills .... 3 

Steam-engine, the windmill and the . 2 
Steam-pumps, the relative economy 

of windmills and 139 

Stevenson on velocity of wind and 

height of observation .... 21 
Storage batteries and the use of 

windmills 4 

Storing air and the use of windmills, 4 

water and the use of windmills . 4 

Stover Windmill 106 

Strong Windmill 115 

Supply, railway water, and the use of 

windmills 4 

Surfaces, effect of wind on plane . . 8 

Table I., showing average movement 
of wind in America 7 

Table II., showing relation between 
temperature, pressure, and velo- 
city of wind 12, 13 

Table III., showing (Rouse-Smeaton) 
relation between pressure and 
velocity of wind 14 

Table IV., Hartnup's compilation of 
highest wind pressures in Great 
Britain 25 

Table V., showing best angles of 
weather 35 

Table VI., showing results of Smea- 
ton's experiments 125 

Table VII., showing capacity of the 
windmill 136 

Table VIII., showing economy of 
the windmill 138 

Table IX., showing economy of 
steam-pumps 140, 141 

Table X., showing economy of Erics- 
son's hot-air engine 144 

Table XI., showing loss, by friction, 
of water in pipes 149 

Table XII., showing co-efficient of 
friction in axles 150 

Table XIII., showing capacity of 
windmill pumps of different 
diameters and strokes . . . .151 



PAGE 

Table XIV., showing class and 
proper diameter of windmill 
pumps 152 

Table XV., showing number of acres 
irrigated by windmills . . . . 1 53 

Table XVI., showing capacity of 
cisterns and tanks 153 

Table XVII., showing dimensions, 
weight, etc, of wrought-iron 
pipes 154 

Tankage required, and the economy 
of windmills 142 

Tanks, capacity of 153 

Temperature, its effect upon the 
pressure of wind 12, 13 

Theoretical mechanical effect of 
windmill sail 33 

Theoretical mechanical effect of 
windmill with plane sails ... 40 

Theoretical mechanical effect of 
windmill with shape of sail for 
maximum effect yj 

Thomson, Sir William, on the use 

of windmills 4, 133 

Tower of Corcoran Windmill ... 82 
or Dutch windmills 63 

Trautwine on high wind pressures in 

America 23 

Types, various, of American wind- 
mills x • 75 

United-States Wind Engine and 

Pump Company 89 

Use of the windmill 1 

extent of, in America 2 

specific 3 

Velocity of wind 5 

as affected by height of observa- 
tion 21 

Velocity of wind as affected by 
height of observation, Archibald 
on 22 

Velocity of wind as affected by 
height of observation, Stevenson 
on 21 

Velocity of wind, average, in Amer- 
ica 7 



i6o 



INDEX. 



PAGE 

Velocity of wind, relation between 

pressure and 9, 12-14 

Velocity of wind, relation between 

pressure and, Field on .... 18 
Velocity of wind, relation between 

pressure and, Hagen on ... 20 
Velocity of wind, relation between 

pressure and, Hawksley on . . 17 
Velocity of wind, relation between 

pressure and, Pole on ... . 19 
Velocity of wind, relation between 

pressure and, Rankine on . . . 16 
Velocity of wind, relation between 

pressure and, Rouse-Smeaton . 14 
Velocity of wind required to drive a 

windmill 8 

Velocity regulation windmills . . .104 

Ventilators, best angles for . . . . 37 

Vertical windmills, 55 

compared to horizontal . . . . 55 

general description of 55 

Water, allowance for friction in pipes, 146 
loss, by friction, in pipes . . . .149 

weight of cubic foot 148 

Weather, best angles of impulse 

and 23 

Wind, definition of 5 

effect of, on plane surfaces ... 8 

effect of barometer on pressure of, 1 1 
effect of temperature on pressure 

of 8 

Wind, high pressure of 22 

impulse of, on windmill blades . . 28 
loss of pressure of, by particles of 

air in motion 10 

Wind, movement and velocity of . . 6 
movement of, in America ... 7 
relation between actual and theo- 
retical pressure of 10 

Wind, relation between height <3f 

observation and velocity of . . 21 

Wind, relation between pressure and * 

velocity of 9 

Wind, velocity and movement of . . 6 
velocity and movement of, in 

America 7 

Wind, velocity and pressure of . . 5 



PACE 

Wind, velocity required to drive a 

windmill 8 

Windmill, acres irrigated by . . .153 

Adams 101 

Althouse 97 

American 74 

and steam-engine 2 

appreciation of 1 

average work of 3 

blades, impulse of wind on ... 28 
blades, impulse of wind on, Ran- 
kine on 30 

Windmill blades, impulse of wind 

on, Weisbach on 31 

Windmill, Buchanan 104 

capacity of 134, 136 

capacity and economy of . . . .132 

Champion 109 

comparison of American and Euro- 
pean 73 

Windmill, Corcoran 78 

Coulomb's experiments on the . . 42 

Eclipse 87 

economy and capacity of the . .131 

economy of the 137, 138 

economy of the, and gas-engine . 144 

economy of the, and hot-air engine, 143 

economy of the, and steam-pump . 139 

experiments on the 122 

experiments on the, Coulomb's . 128 

experiments on the, Smeaton's. . 123 

Halladay 89 

Leffel 119 

pumps, capacity of 151 

pumps, class and diameter of . .152 

Regulator in 

sails, Cubitt's method of reefing . 70 

sails, description of European . . 57 

sails, Meikle's method of reefing . 69 
sails, theoretical mechanical effect 

of 33 

Windmill sails, theoretical mechan- 
ical effect of, shape for maximum 

effect 37 

Windmill sails, the mechanical effect 

of plane 40 

Windmill, specific uses of the . . , j, 4 

Stover 106 



INDEX. 



161 



Windmill, Strong 115 

use of the 1 

useful data in connection with 

practice 146 

Windmill, velocity of wind required 

to drive 8 

Windmill, velocity-regulation . . .104 

Windmill, Woodmanse 106 

Windmills, Dutch or tower .... 63 

early history of 45 

economical motors 1 

European 52 

German or post 60 



PACK 

Windmills, horizontal 52 

horizontal, compared to vertical . 55 

horizontal, description of . ... 52 

horizontal, disadvantages of . . 54 

post or German ... ... 60 

sizes of 137 

Thomson, Sir William, on use 

of 4, 133 

Windmills, tower or Dutch .... 63 

types of 75 

vertical 55 

Woodmanse Windmill 106 

Wrought-iron pipe, weight of . . .154 



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OF THE 

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Jackson's Directions for Laboratory Work in Physiological Chemistry. .8vo, z 25 

Keep's Cast Iron 8vo, 2 50 

Ladd's Manual of Quantitative Chemical Analysis nmo, 1 00 

Landauer's Spectrum Analysis. (Tingle.) 8vo, 3 00 

* Langworthy and Austen. The Occurrence of Aluminium in Vege able 

Products, Animal Products, and Natural Waters 8vo, 2 00 

Lassar-Cohn's Practical Urinary Analysis. (Lorenz.) nmo, z 00 

Application of Some General Reactions to Investigations in Organic 

Chemistry. (Tingle.) niro, z 00 

Leach's The Inspection and Analysis of Food with Special Reference to State 

Control 8vo, 7 50 

Lob's Electrolysis and Electrosynthesis of Organic Compounds. (Lorenz.). 1 2mo, 1 00 
Lodge's Notes on Assaying and Metallurgical Laboratory Experiments. .. .8vo, 

Lunge's Techno-chemical Analysis. (Cohn.) 12 mo, 

Mandel's Handbook for Bio-chemical Laboratory nmo, 

* Martin's Laboratory Guide to Qualitative Analysis with the Blowpipe . . nmo, 
Mason's Water-supply. (Considered Principally from a Sanitary Standpoint.) 

3d Edition, Rewritten 8vo, 

Examination of Water. (Chemical and Bacteriological) 12 mo, 

Matthew's The Textile Fibres 8vo, 

Meyer's Determination of Radicles in Carbon Compounds. (Tingle.). . nmo, 

Miller's Manual of Assaying nmo, 

Mixter's Elementary Text-book of Chezpistry. nmo, 

Morgan's Outline of Theory of Solution and its Results nmo, 

Elements of Physical Chemistry nmo, 

Morse's Calculations used in Cane-sugar Factories i6mo, morocco, 

Mulliken's General Method for the Identification of Pure Organic Compounds. 

Vol. I Large 8vo, 

O'Brine's Laboratory Guide in Chemical Analysis 8vo, 

O'DriscolTs Notes on the Treatment of Gold Ores 8vo, 

Ostwald's Conversations on Chemistry. Part One. (Ramsey.) nmo, 

Ostwald's Conversations on Chemistry. Part Two. (TurnbulL). (In Press.) 

* Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 

8vo, paper, 

Pictet's The Alkaloids and their Chemical Constitution. (Biddle.) 8vo, 

Pinner's Introduction to Organic Chemistry. (Austen.) nmo, 

Poole's Calorific Power of Fuels 8vo, 

Prescott and Winslow's Elements of Water Bacteriology, with Special Refer- 
ence to Sanitary Water Analysis nmo. 

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* Reisig's Guide to Piece-dyeing 8vo. 15 00 

Richards and Woodman's Air, Water, and Food from a Sanitary Standpoint 8vo, 2 00 

Richards's Cost of Living as Modified by Sanitary Science i2irc, x 00 

Cost of Food, a Study in Dietaries i2mo, 1 00 

* Richards and Williams's The Dietary Computer 8vo, 1 50 

Ricketts and Russell's Skeleton Notes upon Inorganic Chemistry. (Part I. 

Non-metallic Elements.) 8vo, morocco, 75 

Ricketts and Miller's Notes on Assaying 8vo, 3 00 

Ri deal's Sewage and the Bacterial Purincat on of Sewage 8vo, 3 50 

Disinfection and the Preservation of Food 8vo, 4 00 

Rigg's Elementary Manual for the Chemical Laboratory 8vo, 1 25 

Rostoski's Serum Diagnosis. (Bolduan.) 12 mo, x 00 

Ruddiman's Incompatibilities in Prescriptions 8vo, 2 00' 

Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 00 

Salkowski's Physiological and Pathological Chemistry. (Orndorff.) 8vo, 2 50 

Schimpf's Text-book of Volumetric Analysis i2mo, 2 50 

Essentials of Volumetric Analysis 12 mo, 1 25 

Spencer's Handbook for Chemists of Beet-sugar Houses x6mo, morocco, 3 00 

Handbook for Sugar Manufacturers and their Chemists. . x6mo, morocco, 2 00 

Stockbridge's Rocks and Soils 8vo, 2 50 

* Tillman's Elementary Lessons in Heat 8vo, 1 50 

: * Descriptive General Chemistry 8vo, 3 00 

TreadwelTs Qualitative Analysis. (Hall.) 8vo, 3 00 

Quantitative Analysis. (Hall.) 8vo, 4 00 

Turneaure and Russell's Public Water-supplies 8vo, 5 00 

Van Deventer's Physical Chemistry for Beginners. (Boltwood.) nmo, 1 50 

* Walke's Lectures on Explosives 8vo, 4 00 

Washington's Manual of the Chemical Analysis of Rocks 8vo, 2 00 

Wassermann's Immune Sera : Hemolysins, Cytotoxins, and Precipitins. (Bol- 
duan.) i2mo, 1 00 

Weh's Laboratory Guide in Qualitative Chemical Analysis 8vo, x 50 

Short Course in Inorganic Qualitative Chemical Analysis for Engineering 

Students i2mo, 1 50 

Text-book of Chemical Arithmetic. (In press.) 

Whipple's Microscopy of Drinking-water. 8vo, 3 50 

Wilson's Cyanide Processes nmo, x 50 

Chlorination Process i2mo, 1 50 

Wulling's Elementary Course in Inorganic, Pharmaceutical, and Medical 

Chemistry nmo, 2 00 

CIVIL ENGINEERING. 
BRIDGES AND ROOFS. HYDRAULICS. MATERIALS OF ENGINEERING. 
RAILWAY ENGINEERING. 

Baker's Engineers' Surveying Instruments ismo, 3 00 

Bixby's Graphical Computing Table y Paper 19$ X24i inches. 25 

** Burr's Ancient and Modern Engineering and the Isthmian Canal. (Postage, 

27 cents additional.) 8vo, 3 50 

Comstock's Field Astronomy for Engineers 8vo, 2 50 

Davis's Elevation and Stadia Tables 8vo, 1 00 

Elliott's Engineering for Land Drainage i2mo, 1 50 

Practical Farm Drainage i2mo, 1 00 

Fiebeger's Treatise on Civil Engineering. (In press.) 

Folwell's Sewerage. (Designing and Maintenance.) 8vo, 3 00 

Freitag's Architectural Engineering. 2d Edition, Rewritten 8vo, 3 50 

French and Ives's Stereotomy 8vo, 2 50 

Goodhue's Municipal Improvements umc, 1 75 

Goodrich's Economic Disposal of Towns' Refuse. . ..• 8vo, 3 50 

Gore's Elements of Geodesy 8vo, 2 50 

Hayford's Text-book of Geodetic Astronomy ftvo, 3 00 

Bering's Ready Reference Tables (Conversion Factors) x6mo, morocco, 2 50- 

5 



Howe's Retaining Walls for Earth i2mo, i 25 

Johnson's (J. B.) Theory and Practice of Surveying Small 8vo, 4 00 

Johnson's (L. J.) Statics by Algebraic and Graphic Methods 8vo, 2 00 

Laplace's Philosophical Essay on Probabilities. (Truscott and Emory.) . ian.o, 2 co 

Italian's Treatise on Civil Engineering. (1873.) (Wood.) 8vo, 5 00 

* Descriptive Geometry. 8vo, 1 50 

Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50 

Elements of Sanitary Engineering 8vo, 2 00 

Herriman and Brooks's Handbook for Surveyors x6mo, morocco, 2 00 

Nugent's Plane Surveying 8vo, 3 50 

Ogden's Sewer Design i2mo, 2 00 

Patton's Treatise on Civil Engineering 8vo half leather, 7 50 

Heed's Topographical Drawing and Sketching 4to, 5 00 

Rideal's Sewage and the Bacterial Purification of Sewai.4 8vo, 3 50 

Siebert and Biggin's Modern Stone-cutting and Masonry 8vo, 1 50 

Smith's Manual of Topographical Drawing. (McMillan.) 8vo, 2 50 

Sondericker's Graphic Statics, with Applications to Trusses, E earns, and Arches. 

8vo, 2 00 

Taylor and Thompson's Treatise on Concrete, Plain and Reinforced Svo, 5 00 

* Trautwine's Civil Engineer's Pocket-book i£mo, mcrccco, 5 00 

Wait's Engineering and Archi ectural Jurisprudence 8vo, 6 00 

Sheep, 6 50 
Law of Operations Preliminary to Construction in Engineering and Archi- 
tecture 8vo, 5 00 

Sheep, 5 50 

Law of Contracts 8vo, 3 00 

Warren's Stereotomy — Problems in Stone-cutting 8vo, 2 50 

Webb's Problems in the Use and Adjustment of Engineering Instruments. 

iomo, morocco, 1 25 

* Wheeler's Elementary Course of Civil Engineering 8vo, 4 00 

Wilson's Topographic Surveying 8vo, 3 50 

BRIDGES AND ROOFS. 

Boiler's Practical Treatise on the Construction of Iron Highway Bridges. .8vo, 2 00 

* Thames River Bridge ' , . 4to, paper, 5 00 

Burr's Course on the Stresses in Bridges and Roof Trusses, Arched Rits, and 

Suspension Bridges 8vo, 3 50 

Burr and Falk's Influence Lines for Bridge and Roof Computations .... 8vo, 3 00 

Du Bois's Mechanics of Engineering. Vol. II Small 4tc, 10 00 

Foster's Treatise on Wooden Trestle Bridges 4to, 5 00 

Fowler's Ordinary Foundations 8vo, 3 50 

Greene's Roof Trusses 8vo, x 25 

Bridge Trusses 8vo, 2 50 

Arches in Wood, Iron, and Stone 8vo, 2 50 

Howe's Treatise on Arches 8vo, 4 00 

Design of Simple Roof-trusses in Wood and Steel 8vo, 2 00 

Johnson, Bryan, and Turneaure's Theory and Practice in the Designing of 

Modern Framed Structures Small 4to, xo 00 

Merriman and Jacoby's Text-book on Roofs and Bridges: 

Part I. Stresses in Simple Trusses 8vo, 2 50 

Part II. Graphic Statics 8vo, 2 50 

Part in. Bridge Design 8vo, 2 50 

Part IV. Higher Structures 8vo, 2 50 

Morison's Memphis Bridge # 4to, 10 00 

Waddell's De Pontibus, a Pocket-book for Bridge Engineers. . i6mo, morocco, 3 00 

Specifications for Steel Bridges nmo, x 25 

Wood's Treatise on the Theory of the Construction of Bridges and Roofs . .8vo, 2 00 
Wright's Designing of Draw-spans: 

Part I. Plate-girder Draws 8vo, 2 50 

Part II. Riveted-truss and Pin-connected Long-span Draws 8vo, 2 50 

Two parts in one volume. 8vo, 3 50 

6 



HYDRAULICS. 

Bazin's Experiments upon the Contraction of the Liquid Vein Issuing from 

an Orifice. (Trautwine.) 8vo, a oo 

Bovey's Treatise on Hydraulics 8vo, 5 00 

Church's Mechanics of Engineering 8vo, 6 oo 

Diagrams of Mean Velocity of Water in Open Channels paper, 1 50 

Coffin's Graphical Solution of Hydraulic Problems x6mo, morocco, a 50 

Flather's Dynamometers, and the Measurement of Power iamo, 3 00 

Folwell's Water-supply Engineering 8vo, 4 00 

Frizell's Water-power 8vo, 5 <x> 

Fuertes's Water and Public Health 12 mo, 1 50 

Water-filtration Works ." . xarno, a 50 

Ganguillet and Kutter's General Formula for the Uniform Flow of Water in 

Rivers and Other Channels. (Hering and Trautwine.) 8vo 4 00 

Hazen's Filtration of Public Water-supply. 8vo, 3 00 

Hazlehurst's Towers and Tanks for Water-works. 8vo, a 50 

Herschel's 1x5 Experiments on the Carrying Capacity of Large, Riveted, Metal 

Conduits 6vo, a 00 

Mason's Water-supply. (Considered Principally from a Sanitary Standpoint.) 

8vo, 4 00 

Merriman's Treatise on Hydraulics 8vo, 5 00 

* Michie's Elements of Analytical Mechanics 8vo, 4 00 

Schuyler's Reservoirs for Irrigation, Water-power, and Domestic Water- 
supply Large 8vo, 5 00 

** Thomas and Watt's Improvement of Rivers. (Post, 44c. additional. ).4to, 6 00 

Turneaure and Russell's Public Water-supplies 8vo, 5 00 

Wegmann's Design and Construction of Dams. 4to, 5 00 

Water-supply of the City of Hew York from 1658 to 1805 4to, 10 00 

Wilson's Irrigation Engineering Small 8vo, 4 00 

Wolff's Windmill as a Prime Mover 8vo, 3 00 

Wood's Turbines. 8vo, a 50 

Elements of Analytical Mechanics 8vo, 3 00 

MATERIALS OF ENGINEERING. 

Baker's Treatise on Masonry Construction .' 8vo, 5 00 

Roads and Pavements . Svo, 5 00 

Black's United States Public Works Oblong 4to, 5 00 

Bovey's Strength of Materials and Theory of Structures Svo. 7 50 

Burr's Elasticity and Resistance of the Materials of Engineering 8vo, 7 so 

Byrne's Highway Construction '. 8vo, 5 00 

Inspection of the Materials and Workmanship Employed in Construction. 

i6mo, 3 00 

Church's Mechanics of Engineering 8vo, 6 00 

Du Bois's Mechanics of Engineering. VoL I Small 4 to, 7 50 

Johnson's Materials of Construction Large 8vo, 6 00 

Fowler's Ordinary Foundations 8vo, 3 50 

Keep's Cast Iron 8vo, a 50 

Lanza's Applied Mechanics 8vo, 7 50 

Marten's Handbook on Testing Materials. (Henning. ) a vols 8vo, 7 50 

Merrill's Stones for Building and Decoration 8vo, 5 00 

Merriman's Text-book on the Mechanics of Materials 8vo, 4 00 

Strength of Materials iamo, x 00 

Metcalf's Steel. A Manual for Steel-users iamo, a 00 

Patton's Practical Treatise on Foundations - 8vo, 5 «• 

Richardson's Modern Asphalt Pavements 8vo, 3 09 

Richey's Handbook for Superintendents of Construction xomo, mor., 4 00 

Rockwell's Roads and Pavements in France iamo, x 25 

7 



Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 00 

Smith's Materials of Machines i2mo, x 00 

Snow's Principal Species of Wood 8vo, 3 5» 

Spalding's Hydraulic Cement nmo, 2 00 

Text-book on Roads and Pavements X2mo, 2 00 

Taylor and Thompson's Treatise on Concrete, Plain and Reinforced 8vo, 5 00 

Thurston's Materials of Engineering. 3 Parts 8vo, 8 00 

Part I. Ilon-metallic Materials of Engineering and Metallurgy 8vo, 2 00 

Part II. Iron and SteeL 8vo, 3 50 

Part m. A Treatise on Brasses, Bronzes, and Other Alloys and their 

Constituents .8vo, 2 50 

Thurston's Text-book of the Materials of Construction 8vo, 5 00 

Tillson's Street Pavements and Paving Materials 8vo, 4 00 

WaddelTs De Pontibus. (A Pocket-book for Bridge Engineers.)- • x6mo, mor., 3 00 

Specifications for Steel Bridges iamo, x 25 

Wood's (De V.) Treatise on the Resistance of Materials, and an Appendix on 

the Preservation of Timber 8vo, 2 00 

Wood's (De V.) Elements of Analytical Mechanics 8vo, 3 00 

Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and 

SteeL 8vo, 4 00 

RAILWAY ENGINEERING. 

Andrew's Handbook for Street Railway Engineers 3x5 inches, morocco, x 25 

Berg's Buildings and Structures of American Railroads 4to, 5 00 

Brook's Handbook of Street Railroad Location x6mo, morocco, x 50 

Butt* s Civil Engineer's Field-book x6mo, morocco, 2 50 

Crandall's Transition Curve x6mo, morocco, 1 50 

Railway and Other Earthwork Tables 8vo, 1 50 

Dawson's "Engineering" and Electric Traction Pocket-book. . x6mo, morocco, 5 00 

Dredge's History of the Pennsylvania Railroad: (1879) Paper, 5 00 

* Drinker's Tunnelling, Explosive Compounds, and Rock Drills. 410, half mor., 25 00 

Fisher's Table of Cubic Yards Cardboard, 25 

Godwin's Railroad Engineers' Field-book and Explorers' Guide. . . x6mo, mor., 2 50 

Howard's Transition Curve Field-book x6mo, morocco, 1 50 

Hudson's Tables for Calculating the Cubic Contents of Excavations and Em- 
bankments 8vo, x 00 

Molitor and Beard's Manual for Resident Engineers i6mo, 1 00 

Nagle's Field Manual for Railroad Engineers i6mo, morocco, 3 00 

Philbrick's Field Manual for Engineers i6mo, morocco, 3 00 

Searles's Field Engineering , x6mo, morocco, 3 00 

Railroad Spiral. i6mo, morocco, 1 50 

Taylor's Prismoidal Formulae and Earthwork 8vo, 1 50 

* Trautwine's Method of Calculating the Cube Contents of Excavations and 

Embankments by the Aid of Diagrams 8vo, 2 00 

The Field Practice of Laying Out Circular Curves for Railroads. 

X2ino, morocco, 2 50 

Cross-section Sheet Paper, 25 

Webb's Railroad Construction i6mo, morocco, 5 00 

Wellington's Economic Theory of the Location of Railways Small 8vo, 5 00 

DRAWING. 

Barr's Kinematics of Machinery 8vo, 2 50 

* Bartlett's Mechanical Drawing 8vo, 3 00 

* " " " Abridged Ed 8vo, 150 

Coolidge's Manual of Drawing 8vo, paper 1 00 

Coolidge and Freeman's Elements of General Drafting for Mechanical Engi- 
neers Oblong 4to, 2 50 

Durley's Kinematics of Machines. 8vo, 4 00 

Emch's Introduction to Projective Geometry and its Applications 8vo. 2 50 

8 



Hill's Text-book on Shades and Shadows, and Perspective 8vo, a oo 

Jamison's Elements of Mechanical Drawing 8vo, 2 50 

Jones's Machine Design : 

Part I. Kinematics of Machinery 8vo, 1 50 

Part n. Form, Strength, and Proportions of Parts 8vo, 3 00 

MacCord's Elements of Descriptive Geometry 8vo, 3 00 

Kinematics; or, Practical Mechanism 8vo, 5 00 

Mechanical Drawing 4to, 4 00 

Velocity Diagrams 8vo, 1 50 

* Mahan's Descriptive Geometry and Stone-cutting 8vo, 1 50 

Industrial Drawing. (Thompson.) 8vo, 3 50 

Moyer's Descriptive Geometry 8vo, 2 00 

Reed's Topographical Drawing and Sketching 4to, 5 00 

Reid's Course in Mechanical Drawing 8vo, 2 00 

Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 00 

Robinson's Principles of Mechanism 8vo, 3 00 

Schwamb and Merrill's Elements of Mechanism 8vo, 3 00 

Smith's Manual of Topographical Drawing. (McMillan.) 8vo, 2 50 

Warren's Elements of Plane and Solid Free-hand Geometrical Drawing. 12 mo, 1 00. 

Drafting Instruments and Operations iamo : z 25 

Manual of Elementary Projection Drawing 12 mo, z 5* 

Manual of Elementary Problems in the Linear Perspective of Form and 

Shadow iamo, 1 00 

Plane Problems in Elementary Geometry i2mo, z 25 

Primary Geometry nmo, 75 

Elements of Descriptive Geometry, Shadows, and Perspective 8vo, 3 50 

General Problems of Shades and Shadows 8vo, 3 00 

Elements of Machine Construction and Drawing 8vo, 7 50 

Problems, Theorems, and Examples in Descriptive Geometry 8vo, 2 50 

Weisbach's Kinematics and Power of Transmission. (Hermann and Klein )8vo, 5 00 

Whelpley's Practical Instruction in the Ait of Letter Engraving i2xno, 2 00 

Wilson's (H. M.) Topographic Surveying 8vo, 3 50 

Wilson's (V. T.) Free-hand Perspective 8vo, 2 50 

Wilson's (V. T.) Free-hand Lettering 8vo, 1 00 

Woolf's Elementary Course in Descriptive Geometry Large 8vo, 3 00 



ELECTRICITY AND PHYSICS. 

Anthony and Brackett's Text-book of Physics. (Magie.) Small 8vo, 3 00 

Anthony's Lecture-notes on the Theory of Electrical Measurements. . . . 12010, x 00 

Benjamin's History of Electricity. 8vo, 3 00 

Voltaic CelL 8vo, 3 00 

Classen's Quantitative Chemical Analysis by Electrolysis. (Boltwood.).8vo, 3 00 

Crehore and Squier's Polarizing Photo-chronograph 8vo, 3 00 

Dawson's "Engineering" and Electric Traction Pocket-book. i6mo, morocco, 5 00 
Dolezalek's Theory of the Lead Accumulator (Storage Battery). (Von 

Ende.) i2mo, 2 50 

Duhem's Thermodynamics and Chemistry. (Burgess.) 8vo, 4 00 

Flather's Dynamometers, and the Measurement of Power ismo, 3 00 

Gilbert's De Magnete. (Mottelay.) 8vo, 2 50 

Hanchett's Alternating Currents Explained 12010, x 00 

Hering's Ready Reference Tables (Conversion Factors) ...... i6mo, morocco, 2 50 

Holman's Precision of Measurements 8vo, 2 00 

Telescopic Mirror-scale Method, Adjustments, and Tests .... Large 8vo, 75 

Kinzbrunner's Testing of Continuous-Current Machines 8vo, 2 00 

Landauer's Spectrum Analysis.- (Tingle.) 8vo, 3 00 

Le Chate lien's High-temperature Measurements. (Boudouard — Burgess.) tamo, 3 00 

Lob's Electrolysis and Electrosynthesis of Organic Compounds. (Lorenz.) i2mo, 1 00 

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* Lyons's Treatise on Electromagnetic Phenomena. Vols. I. and II. 8vo, each, 6 00 

* Michie's Elements of Wave Motion Relating to Sound and Light 8vo, 4 00 

Niaudet's Elementary Treatise on Electric Batteries. (Fishback.) nmo, 2 50 

* Rosenberg's Electrical Engineering. (Haldane Gee — Kinzbrunner.). . .8vo f 1 50 

Ryan, Norris, and Hozie's Electrical Machinery. Vol. 1 8vo, 2 50 

Thurston's Stationary Steam-engines 8vo, 2 50 

* Tillman's Elementary Lessons in Heat 8vo, 1 50 

Tory and Pitcher's Manual of Laboratory Physics Small 8vo t 2 00 

Ulke's Modern Electrolytic Copper Refining 8vo, 3 00 

LAW. 

* Davis's Elements of Law 8vo, 

* Treatise on the Military Law of United States. 8vo, 

* Sheep, 

Manual for Courts-martial. x6mo, morocco, 

Wait's Engineering and Architectural Jurisprudence 8vo, 

. Sheep, 
Law of Operations Preliminary to Construction in Engineering and Archi- 
tecture 8vo, 

Sheep, 

Law of Contracts. 8vo, 

Winthrop's Abridgment of Military Law i2mo, 

MANUFACTURES. 

Bernadou's Smokeless Powder — Nitro-cellulose and Theory of the Cellulose 

Molecule nmo, 2 50 

Bolland's Iron Founder i2mo, 2 50 

" The Iron Founder," Supplement i2mo, 2 50 

Encyclopedia of Founding and Dictionary of Foundry Terms Used in the 

Practice of Moulding nmo, 3 00 

Eissler's Modern High Explosives 8vo, 4 00 

Effront's Enzymes and their Applications. (Prescott.) 8vo, 3 00 

Fitzgerald's Boston Machinist nmo, z 00 

Ford's Boiler Making for Boiler Makers. .... i8mo, x 00 

Hopkin's Oil-chemists' Handbook. 8vo, 3 00 

Keep's Cast Iron 8vo, 2 50 

Leach's The Inspection and Analysis of Food with Special Reference to State 

Control Large 8vo, 7 50 

Matthews's The Textile Fibres 8vo, 3 50 

Metcalf's Steel A Manual for Steel-users nmo, 2 00 

Metcalfe's Cost of Manufactures — And the Administration of Workshops . 8vo, 5 00 

Meyer's Modern Locomotive Construction. 4to, 10 00 

Morse's Calculations used in Cane-sugar Factories i6mo, morocco, x 50 

* Reisig's Guide to Piece-dyeing 8vo, 25 00 

Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 00 

Smith's Press-working of Metals 8vo, 3 00 

Spalding's Hydraulic Cement nmo, 2 00 

Spencer's Handbook for Chemists of Beet-sugar Houses. . . . i6mo, morocco, 3 00 

Handbook for Sugar Manufacturers and their Chemists . . i6mo, morocco, 2 00 

Taylor and Thompson's Treatise on Concrete, Plain and Reinforced 8vo, 5 00 

Thurston's Manual of Steam-boilers, their Designs, Construction and Opera- 
tion 8vo, 5 00 

* Walke's Lectures on Explosives : .8vo, 4 00 

Ware's Manufacture of Sugar. (In press.) 

West* s American Foundry Practice i2mo, 2 50 

Moulder's Text-book i2mo, 2 50 

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Wolff's Windmill as a Prime Mover 8vo, 3 00 

Wood's Rustless Coatings: Corrosion and Electrolysis of Iron and Steel. 8vo, 4 00 

MATHEMATICS. 

Baker's Elliptic Functions 8vo, r 50 

* Bass's Elements of Differential Calculus i2mo, 4 00 

Briggs's Elements of Plane Analytic Geometry 1 21110 , 1 00 

Compton's Manual of Logarithmic Computations 12 mo, 1 50 

Davis's Introduction to the Logic of Algebra 8vo, 1 50 

* Dickson's College Algebra Large i2mo, 1 50 

* Introduction to the Theory of Algebraic Equations Large i2mo, 1 25 

Emch's Introduction to Projective Geometry and its Applications 8vo, 2 50 

Halsted's Elements of Geometry 8vo, 1 75 

Elementary Synthetic Geometry 8vo, 1 50 

Rational Geometry nmo, 1 75 

* Johnson's (J. B.) Three-place Logarithmic Tables: Vest-pocket size. paper, 15 

100 copies for 5 00 

* Mounted on heavy cardboard, 8 X 10 inches, 25 

10 copies for 2 00 

Johnson's (W. W.) Elementary Treatise on Differential Calculus . . Small 8vo, \ 00 

Johnson's (W. W.) Elementary Treatise on the Integral Calculus . Small 8vo, 1 50 . 

Johnson's (W. W.) Curve Tracing in Cartesian Co-ordinates i2mo, 1 00 

Johnson's (W. W.) Treatise on Ordinary and Partial Differential Equations. 

Small 8vo, 3 50 

Johnson's (W. W.) Theory of Errors and the Method of Least Squares, nmo, 1 50 

* Johnson's (W. W.) Theoretical Mechanics i2mo, 3 00 

Laplace's Philosophical Essay on Probabilities. (Truscott and Emory.), nmo, 2 00 

* Ludlow and Bass. Elements of Trigonometry and Logarithmic and Other 

Tables 8vo, 3 00 

Trigonometry and Tables published separately Each, 2 00 

* Ludlow's Logarithmic and Trigonometric Tables 8vo, 1 00 

Maurer's Technical Mechanics 8» , 4 00 

Merriman and Woodward's Higher Mathematics 8vo, 5 00 

Merriman's Method of Least Squares 8vo, 2 00 

Rice and Johnson's Elementary Treatise on the Differential Calculus. . Sm. 8vo, 3 00 

Differential and Integral Calculus. 2 vols, in one Small 8vo, 2 50 

Wood's Elements of Co-ordinate Geometry 8vo, 2 00 

Trigonometry: Analytical, Plane, and Spherical nmo, 1 00 



MECHANICAL ENGINEERING. 

MATERIALS OF ENGINEERING, STEAM-ENGINES AND BOILERS. 

Bacon's Forge Practice nmo, 1 50 

Baldwin's Steam Heating for Buildings nmo, 2 50 

Barr's Kinematics of Machinery 8vo, 2 50 

* Bartlett's Mechanical Drawing 8vo, 3 00 

* " " " Abridged E1 8vo, 150 

Benjamin's Wrinkles and Recipes 12 mo, 2 00 

Carpenter's Experimental Engineering 8vo, 6 00 

Heating and Ventilating Buildings 8vo, 4 00 

Cary's Smoke Suppression in Plants using Bituminous Coal. (In Prepara- 
tion.) 

Clerk's Gas and Oil Engine Small 8vo, 4 00 

Coolidge's Manual of Drawing 8vo, paper, 1 00 

Coolidge and Freeman's Elements of General Drafting for Mechanical En- 
gineers Oblong 4to, a 50 

11 



Cromwell's Treatise on Toothed Gearing nmo, x 50 

Treatise on Belts and Pulleys 12 mo, 1 50 

Durley's Kinematics of Machines 8vo, 4 op 

Flather's Dynamometers and the Measurement of Power 12010, 3 00 

Rope Driving. 12 mo, 2 00 

Gill's Gas and Fuel Analysis for Engineers 12 mo, x 25 

Hall's Car Lubrication. i2mo, 1 00 

Hering's Ready Reference Tables (Conversion Factors) i6mo, morocco, 2 50 

Hutton's The Gas Engine 8vo, 5 00 

Jamison's Mechanical Drawing 8vo, 2 50 

Jones's Machine Design : 

Part L Kinematics of Machinery 8vo f 1 50 

Part IL Form, Strength, and Proportions of Parts 8vo, 3 00 

Kent's Mechanical Engineers' Pocket-book. . , z6mo, morocco, 5 00 

Kerr's Power and Power Transmission 8vo, 2 00 

Leonard's Machine Shop, Tools, and Methods. (In press.) 

Lorenz's Modern Refrigerating Machinery. (Pope, Haven, and Dean.) (In press.) 

MacCord's Kinematics; or, Practical Mechanism. 8vo, 5 00 

Mechanical Drawing 4 to, 4 00 

Velocity Diagrams 8vo, 1 50 

Mahan's Industrial Drawing. (Thompson.) 8vo, 3 50 

Poole's Calorific Power of Fuels 8vo, 3 00 

Reid's Course in Mechanical Drawing 8vo, 2 00 

Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 00 

Richard's Compressed Air nmo, 1 50 

Robinson's Principles of Mechanism 8vo, 3 00 

Schwamb and Merrill's Elements of Mechanism 8vo, 3 00 

Smith's Press-working of Metals 8vo, 3 00 

Thurston's Treatise on Friction and Lost Work in Machinery and Mill 

Work 8vo, 3 00 

Animal as a Machine and Prime Motor, and the Laws of Energetics . nmo, 1 00 

Warren's Elements of Machine Construction and Drawing 8vo, 7 50 

Weisbach's Kinematics and the Power of Transmission. (Herrmann — 

Klein.) 8vo, 5 00 

Machinery of Transmission and Governors. (Herrmann — Klein.). .8vo, 5 00 

Wolff's Windmill as a Prime Mover 8vo, 3 00 

Wood's Turbines 8vo, 2 50 



MATERIALS OF ENGINEERING. 

Bovey's Strength of Materials and Theory of Structures 8vo, 7 50 

Burr's Elasticity and Resistance of the Materials of Engineering. 6th Edition. 

Reset 8vo, 7 5® 

Church's Mechanics of Engineering 8vo, 6 00 

Johnson's Materials of Construction 8vo, 6 00 

Keep's Cast Iron 8vo, 2 50 

Lanza's Applied Mechanics. 8vo, 7 50 

Martens's Handbook on Testing Materials. (Henning.) 8vo, 7 50 

Merriman's Text-book on the Mechanics of Materials 8vo, 4 00 

Strength of Materials i2mo, 1 00 

Metcalf's Steel. A manual for Steel-users 12 mo. 2 00 

Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 00 

Smith's Materials of Machines i2mo, 1 00 

Thurston's Materials of Engineering 3 vols., 8vo, 8 00 

Part II. Iron and Steel. 8vo, 3 5o 

Part IH. A Treatise on Brasses, Bronzes, and Other Alloys and their 

Constituents 8vo, 2 50 

Text-book of the Materials of Construction 8vo, 5 00 

12 



Wood's (De V.) Treatise on the Resistance of Materials and an Appendix on 

the Preservation of Timber 8vo, 2 00 

Wood's (De V.) Elements of Analytical Mechanics 8vo, 3 00 

Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and 

SteeL 8vo, 4 00 



STEAM-ENGINES AND BOILERS. 

Berry's Temperature-entropy Diagram. iamo, 1 25 

Carnot's Reflections on the Motive Power of Heat (Thurston.) iamo, 1 50 

Dawson's "Engineering" and Electric Traction Pocket-book i6mo, mor., 5 00 

Ford's Boiler Making for Boiler Makers i8mo, 1 00 

Goss's Locomotive Sparks 8vo, 2 00 

Hemenway's Indicator Practice and Steam-engine Economy iamo, 2 00 

Hutton's Mechanical Engineering of Power Plants 8vo, 5 00 

Heat and Heat-engines 8vo f 5 00 

Kent's Steam boiler Economy 8vo, 4 00 

Kneass's Practice and Theory of the Injector 8vo, 1 50 

MacCord's Slide-valves 8vo, 2 00 

Meyer's Modern Locomotive Construction 4 to, 10 00 

Peabody's Manual of the Steam-engine Indicator iamo. r 50 

Tables of the Properties of Saturated Steam and Other Vapors 8vo, 1 00 

Thermodynamics of the Steam-engine and Other Heat-engines 8vo, 5 00 

Valve-gears for Steam-engines 8vo, 2 50 

Peabody and Miller's Steam-boilers .8vo, 4 00 

Pray's Twenty Years with the Indicator Large 8vo, 2 50 

Pupin's Thermodynamics of Reversible Cycles in Gases and Saturated Vapors. 

(Osterberg.) 12 mo, 1 25 

Reagan's Locomotives: Simple Compound, and Electric 12 mo, 2 50 

Rontgen's Principles of Thermodynamics. (Du Bois.) 8vo, 5 00 

Sinclair's Locomotive Engine Running and Management 12 mo, 2 00 

Smart's Handbook of Engineering Laboratory Practice nmo, 2 50 

Snow's Steam-boiler Practice 8vo, 3 00 

Spangler's Valve-gears 8vo f 2 50 

Notes on Thermodynamics i2mo, 1 00 

Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 3 00 

Thurston's Handy Tables 8vo, 1 50 

Manual of the Steam-engine 2 vols., 8vo, 10 00 

Part I. History, Structure, and Theory 8vo, 6 00 

Part II. Design, Construction, and Operation 8vo, 6 00 

Handbook of Engine and Boiler Trials, and the Use of the Indicator and 

the Prony Brake 8vo, 5 00 

Stationary Steam-engines 8vo, 2 50 

Steam-boiler Explosions in Theory and in Practice i2mo, 1 50 

Manual of Steam-boilers, their Designs, Construction, and Operation 8vo, 5 00 

Weisbach's Heat, Steam, and Steam-engines. (Du Bois.) 8vo, 5 00 

Whitham's Steam-engine Design 8vo, 5 00 

Wilson's Treatise on Steam-boilers. (Flather.) 16 mo, 2 50 

Wood's Thermodynamics, Heat Motors, and Refrigerating Machines. . .8vo, 4 00 



MECHANICS AND MACHINERY. 

Barr's Kinematics of Machinery 8vo, 2 50 

Bovey's Strength of Materials and Theory of Structures 8vo, 7 50 

Chase's The Art of Pattern-making iamo, 2 50 

Church's Mechanics of Engineering 8vo, 6 00 

13 



Church's Notes and Examples in Mechanics 8vo, 2 00 

Compton's First Lessons in Metal- working i2mo, 1 50 

Compton and De Groodt's The Speed Lathe 123:0, i 50 

Cromwell's Treatise on Toothed Gearing i2inc, : 50 

Treatise on Belts and Pulleys i2mo, 1 50 

Dana's Text-book of Elementary Mechanics for Colleges and Schools. . i2mo, 1 50 

Dingey's Machinery Pattern Making nmo, 2 00 

Dredge's Record of the Transportation Exhibits Building of the World's 

Columbian Exposition of 1893 4to half morocco, 5 00 

Du Bois's Elementary Principles of Mechanics : 

Vol. I. Kinematics .8vo, 3 50 

Vol. II. Statics 8vo, 4 00 

VoL III. Kinetics 8vo, 3 50 

Mechanics of Engineering. VoL I Small 4to, 7 50 

VoL II Small 4to, 10 00 

Durley's Kinematics of Machines 8vo, 4 00 

Fitzgerald's Boston Machinist x6mo, 1 00 

F lather's Dynamometers, and the Measurement of Power i2mo, 3 00 

Rope Driving x2mo, 2 00 

Goss's Locomotive Sparks 8vo, 2 00 

Hall's Car Lubrication. iamo, 1 00 

Holly's Art of Saw Filing x8mo, 75 

James's Kinematics of a Point and the Rational Mechanics of a Particle. Sm.8vc,2 00 

* Johnson's (W. W.) Theoretical Mechanics i2mo, 3 00 

Johnson's (L. J.) Statics by Graphic and Algebraic Methods 8vo, 2 00 

Jones's Machine Design: 

Part I. Kinematics of Machinery 8vo, 1 50 

Part H. Form, Strength, and Proportions of Parts 8vo, 3 00 

Kerr's Power and Power Transmission. 8vo, 2 00 

Lanza's Applied Mechanics 8vo, 7 50 

Leonard's Machine Shop, Tools, and Methods. (In press.) 

Lorenz's Modern Refrigerating Machinery. (Pope, Haven, and Dean.) (In press.) 

MacCord's Kinematics; or, Practical Mechanism 8vo, 5 00 

Velocity Diagrams 8vo, 

Maurer's Technical Mechanics 8vo f 

Merriman's Text-book on the Mechanics of Materials 8vo, 

* Elements of Mechanics nmo, 

* Michie's Elements of Analytical Mechanics 8vo, 

Reagan's Locomotives: Simple, Compound, and Electric 12 mo, 

Reid's Course in Mechanical Drawing 8vo, 

Text-book of Mechanical Drawing and Elementary Machine Design. 8 vo, 

Richards's Compressed Air nmo, 

Robinson's Principles of Mechanism 8vo, 

Ryan, Norris, and Hoxie's Electrical Machinery. VoL 1 8vo, 

Schwamb and Merrill's Elements of Mechanism 8vo, 

Sinclair's Locomotive-engine Running and Management nmo, 

Smith's (0.) Press-working of Metals 8vo, 

Smith's (A. W.) Materials of Machines nmo, 

Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 

Thurston's Treatise on Friction and Lost Y/ork in Machinery and Mill 
Work 8vo. 

Animal as a Machine and Prime Motor, and the Laws of Energetics. 

1 2 mo, 

Warren's Elements of Machine Construction and Drawing 8vo, 

Weisbach's Kinematics and Power of Transmission. (Herrmann — Klein. ) . 8vo, 

' Machinery of Transmission and Governors. (Herrmann — Klein. ).8vo, 

Wood's Elements of Analytical Mechanics 8vo, 

Principles of Elementary Mechanics i2mo, 

Turbines 8vo. 

The World's Columbian Exposition of 1893 4to, 

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METALLURGY, 

Egleston's Metallurgy of Silver, Gold, and Mercury: 

Vol. I. Silver 8vo, 7 50 

Vol. II. Gold and Mercury 8vo, 7 50 

** Iles's Lead-smelting. (Postage 9 cents additional) i2mo, 2 50 

Keep's Cast Iron 8vo, 2 30 

Kunhardt's Practice of Ore Dressing in Europe 8vo, 1 50 

Le Chatelier's High-temperature Measuremep ts. ( Boudouard — Burgess. ) 1 2 mo , 3 00 

Metcalf' s SteeL A Manual for Steel-users nmo, 2 00 

Smith's Materials of Machines i2mo, 1 00 

Thurston's Materials of Engineering. In Three Parts 8vo, 8 00 

Part II. Iron and SteeL 8vo. 3 50 

Part HX A Treatise on Brasses, Bronzes, and Other Alloys and their 

Constituents 8vo, 2 50 

Ulke's Modern Electrolytic Copper Refining 8vo, 3 00 

MINERALOGY. 

Barringer's Description of Minerals of Commercial Value. Oblong, morocco, 2 50 

Boyd's Resources of Southwest Virginia 8vo, 3 00 

Map of Southwest Virignia Pocket-book form. 2 00 

Brush's Manual of Determinative Mineralogy. (Pen field.) 8vo, 4 00 

Chester's Catalogue of Minerals 8vo, paper, i 00 

Cloth, 1 25 

Dictionary of the Names of Minerals 8vo, 3 50 

Dana's System of Mineralogy Large 8vo, half leather, 12 50 

First Appendix to Dana's New " System of Mineralogy." Large 8vo, 1 00 

Text-book of Mineralogy 8vo, 4 00 

Minerals and How to Study Them nmo, 1 50 

Catalogue of American Localities of Minerals Large 8vo, 1 00 

Manual of Mineralogy and Petrography i2mo 2 00 

Douglas's Untechnical Addresses on Technical Subjects i2mo, x 00 

Eakle's Mineral Tables 8vo, 1 25 

Egleston's Catalogue of Minerals and Synonyms 8vo, 2 50 

Hussak's The Determination of Rock-forming Minerals. (Smith.). Small 8vo. 2 00 

Merrill's Non-metallic Minerals: Their Occurrence and Uses 8vo, 4 00 

* Ptnfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 

• 8vo. paper, o 50 
Rosfmbusch's Microscopical Physiography of the Rock-making Minerals. 

(Iddings.) 8vo. 5 00 

* Tillman's Text-book of Important Minerals and Rocks 8vo. 2 00 

Willi* ais's Manual of Lithology 8vo, 3 00 

MINING. 

Beard'* Ventilation of Mines. i2mo. 

Boyd's Resources of Southwest Virginia 8vo. 

M«.p of Southwest Virginia Pocket book form. 

Douglas's Untechnical Addresses on Technical Subjects 12 mo. 

* Dririer's Tunneling, Explosive Compounds, and Rock Drills. .4to.hf. mor 

Eissler'6 Modern High Explosives 8vo . 

Fowler's Sewage Works Analyses i2mo 

Goody ear's Coal-mines of the Western Coast of the United States nmo. 

Ihlseng's Manual of Mining 8vo. 

** Iles's Lead-smelting. (Postage 9c. additional.) i2mo. 

Kunhardt's Practice of Ore Dressing in Europe .8vo, 

O'DriscoIl's Notes on the Treatment of Gold Ores : .8vo, 

* Walkc'* Lectures on Explosives . . 8vo, 

Wilson's Cyanide Processes nrno, 

Chk rnation Process xamo, 

16 



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Wilson's Hydraulic and Placer Mining nmo, 2 00 

Treatise on Practical and Theoretical Mine Ventilation iamo. 1 25 

SANITARY SCIENCE. 

FolwelTs Sewerage. (Designing, Construction, and Maintenance.) 8vo, 3 00 

Water-supply Engineering 8vo, 4 00 

Fuertes's Water and Public Health \ iamo, 1 50 

Water-filtration Works i2mo, 2 50 

Gerhard's Guide to Sanitary House-inspection i6mo, 1 00 

Goodrich's Economic Disposal of Town's Refuse Demy 8vo, 3 50 

Hazen's Filtration of Public Water-supplies 8vo, 3 00 

Leach's The Inspection and Analysis of Food with Special' Reference to State 

Control 8vo, 7 50 

Mason's Water-supply. (Considered principally from a Sanitary Standpoint) 8vo, 4 00 

Examination of Water. (Chemical and Bacteriological) 12 mo, 1 25 

Merriman's Elements of Sanitary Engineering 8vo, 2 00 

Ogden's Sewer Design 12 mo, 2 00 

Prescott and Winslow's Elements of Water Bacteriology, with Special Refer- 
ence to Sanitary Water Analysis i2mo, 1 25 

* Price's Handbook on Sanitation nmo, 1 50 

Richards's Cost of Food. A Study in Dietaries nmo, 1 00 

Cost of Living as Modified by Sanitary Science i2mo, 1 00 

Richards and Woodman's Air, Water, and Food from a Sanitary Stand- 
point 8vo, 2 00 

* Richards and Williams's The Dietary Computer 8vo, 1 50 

Rideal's Sewage and Bacterial Purification of Sewage 8vo, 3 50 

Turneaure a~d Russell's Public Water-supplies 8vo, 5 00 

Von Behring's Suppression of Tuberculosis. (Bolduan.) iamo, 1 00 

Whipple's Microscopy of Drinking-water 8vo, 3 50 

Woodhull's Notes on Military Hygiene i6mo, 1 50 

MISCELLANEOUS. 

De Fursac's Manual of Psychiatry. (Rosanoff and Collins.) Large 121110, 2 50 

Emmons's Geological Guide-book of the Rocky Mountain Excursion of the 

International Congress of Geologists Large 8vo, 1 50 

Fen-el's Popular Treatise on the Winds 8vo. 4 00 

Haines's American Railway Management i2mo, 2 50 

Mott's Composition, Digestibility, and Nutritive Value of Food. Mounted chart, 1 25 

Fallacy of the Present Theory of Sound i6mo, 1 00 

Ricketts's History of Rensselaer Polytechnic Institute, 182 4-1 894. .Small 8vo, 3 00 

Rostoski's Serum Diagnosis. (Bolduan.) X2mo, 1 00 

Rotherham's Emphasized New Testament Large 8vo, 2 00 

Steel's Treatise on the Diseases of the Dog 8vo, 3 50 

Totten's Important Question in Metrology 8vo. 2 50 

The World's Columbian Exposition of 1893 4to, 1 00 

Von Behring's Suppression of Tuberculosis. (Bolduan.) i2mo, 1 00 

Winslow's Elements of Applied Microscopy i2mo, 1 50 

Worcester and Atkinson. Small Hospitals, Establishment and Maintenance; 

Suggestions for Hospital Architecture : Plans for Small Hospital . 1 2 mo , 1 25 

HEBREW AND CHALDEE TEXT-BOOKS. 

Green's Elementary Hebrew Grammar i2mo, 1 2$ 

Hebrew Chrestomathy 8vo, 2 00 

Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scriptures. 

(Tregelles.) Small 4to, half morocco, 5 00 

Letter's Hebrew Bible. . 8 ™, 2 25 

16 



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