THE

CHICAGO CONFERENCE

ON

AERIAL NAVIGATION.

BY

DR. W. POLE, F,R.S., M. INsT. C.E., HONORARY SECRETARY.

By permission of'the Council.

Excerpt MinutesofProceedingsof The Institution of Oivil Engineers,

VoL cxxiv. Session 1895-96. Part ii.

Edited by JAMES FORREST, Secretary.

LONDON:

li)ubIisfjell bp tbe institution,GREAT GEORGE STREET, WESTMINSTER, S.W.

[TELEGRAMS, "INSTITUTION, LONDON." TIU,EPHONE," 3051."J

1896..

(A"",yJ

[The right oj Publicati® and oj TranBlatio'lf, iB 9'tlSe1'ood.]

ADVERTISEMENT.

The Institution as a body IS not responsible either for the statements

made, or for the opinions expressed, in the following pages.� .

LONDON; PRINTR)) BY w�r. CLOWRS AND SONS, LUUTEn, s·rAMFORn STREET AND CHARING aRO),;!'!.

THE INSTITUTION OF CIVIL ENGINEERS.

SECT. II�-OTHER SELEOTED PAPERS.

(Paper No. 2937.)"The Chicago Conference on Aerial Navigation."

By Dr. W. POLE, F.R.S., M. Inst. O.E., Honorary Secretary.AMONG the many curious novelties presented to the world at

the great Ohicago Exhibition of 1893, was an "InternationalConference on Aerial Navigation," and its occurrence marks a

modern step in engineering science.The question" whether man, the creature of the earth, can

ever attain to the empire of the air, as he has already attainedto the empire of the sea," is one of the oldest that has interestedcivilized society; but it is only within the last few years thatit has been considered worthy of scientific study. 'I'he attempts,early begun and long continued, at imitating the birds were

always found to be failures; and, though the invention of the

balloon appeared to make the problem easier, yet the main

object, namely, motion in a voluntarily controlled direction,seemed as far off as ever. Indeed, the idea was, not unfrequently,pronounced to be a physical impossibility. But Lavoisier had

pointed out on what principles a balloon might be guided; and,some quarter of a century ago, attempts were made to carrythese principles into practice. The Author of this Paper believeshe was the first person to describe these attempts to Englishreaders, and to predict, in reasonings and calculations laidbefore this Institution, that they contained the promise of what

might, before long, prove to be a practical means of aeriallocomotion.'

Further trials verified his predictions, and now voluntarylocomotion through the air is admitted as a fit subject for

engineering study, like that on the land or on the water.

There had been some kind of meeting on the subject at Paris

in 1889, when the Government war-balloon was. exhibited, andthis gave the idea that the subject was being studied in various

1 "Quarterly Review," July 1875; "Fortnightly Review," Jan. 1881;Minutes of Proceedings Inst. C.E., vol. lxvii., Session 1881-82, page 369, andvol. lxxxi., Session 1884:-85, page 233.

4 POLE ON OHIOAGO OONFERENOE ON AERIAL NAVIGATION. [Selected

parts of Europe; but the Chicago Conference was much more pre­tentious, and it may be interesting 'to give some idea of what was

done there. The following particulars are extracted from a largeand closely printed volume of the Proceedings.'

The Conference lasted four days, and its proceedings were

directed by a committee of

The World's Oongress, Auxiliary of the World's Oolumbian

Exposition of 1893: Department ofEngineering.The objects were: to bring about the discussion of some of "the

scientific problems involved; to collate the results of the latest

researches; to procure an interchange of ideas; and to promoteconcert of action among the students of this inchoate subject.

The general arrangement was to include three main topics.I. SCIENTIFIC PRINCIPLES: such as the properties of the air;

propellers and motors; materials of construction; and generalstructural forms.

II. AVlATION: meaning the discussion and imitation of theflight of birds; and the subject of flying machines generally.

III. BALLOONING: the construction and principles of action of

balloons; and their probable improvement.The Conference was opened by an address from Mr. O. Chanute,

Civil Engineer, of Chicago, who had published a lecture on the

subject given in Cornell University in 1890.2 He gave a lucidaccount of the state of knowledge on the subject generally, afterwhich many Papers were read and discussed. Thirty-eight are

printed, wholly or partially, in the volume above mentioned,following no order of subjects; but it will be more convenient hereto notice the most prominent matter they contain on the three

heads of division above given.

I. GENERAL SCIENTIFIC PRINCfPLES.

The first Paper published is a long and elaborate one by a youngengineer, Mr. C. W. Hastings of Chicago, who unhappily died

before the date of the Conference. Without describing any par­ticular apparatus, the author investigates the general subjects of

1 Proceedings of the International Conference on Aerial Navigation, held in

Chicago, Angust 1, 2, 3 and 4, 1893. Published by the American Engineerand Railroad Journal, New York, 1894.

2 Neither Mr. Chanute nor anyone else who took part in the Conference

appears to have been aware of any of the previous publications on the subjectin this country.-W. P.

Papers.] POLE.ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. 5

balloon flight, and of mechanical flight, dividing the latter intothe two branches of orthogonal or "beating" flight, and of glidingor " sailing" flight, arid noticing the supporting surface, its out­

line, character and shape, and the stability of the structure. Hethen goes into the discussion of the power required, the motive

instrument, particularly the screw propeller, and then thevarieties of modes of producing and applying the motive power.All these matters are elaborately discussed, with mathematicaltreatment when necessary, and the Paper on the whole is an

extremely interesting one.

The next Paper is also a' long one, remarkably original, byProfessor S. P. 'Langley, who was previously well known in regardto the subject by his striking" Experiments in Aerodynamics"in 1891, which threw a new light on the motion of certainforms of bodies through the atmosphere, and offered much en­

couragement to the further study of dynamic flight,"Professor Langley's Oonference Paper is entitled" The Internal

Work of the Wind;" the following extract will show its object.He says:-

" It has long been observed that certain species of birds maintain themselves

indefinitely in the air by soaring, without any flapping of the wing or any motionother than a slight rocking of the body; and this, although the body in questionis many hundred times denser than the air in which it seems to float, with an

undulating movement, as on the wave of an invisible stream .

• , No satisfactory mechanical explanation of this anomaly has been given, andnone would be offered in this connection by the writer were he not satisfied thatit involves much more than an ornithological problem, and that it points to novelconclusions of mechanical and utilitarian importance. They are paradoxical atfirst sight, since they imply that, under certain specified conditions, very heavybodies, entirely detached from the earth, immersed in and free to move in the

air, can be sustained there indefinitely without any expenditure of energy fromwithin." ...

" The writer, like others, has satisfied himself by repeated observations, thatthe soaring vultures and other birds appear as if sustained by some invisiblesupport in the stream of air, sometimes for at least a considerable fraction ofan hour." ...

" This, it might seem, is, without misuse of language, to be called a physicalmiracle."

The author cites the work of L. P. Mouillard "L'Empire del'Air" in support of these facts; and he then states at some

length how he was led to conjecture where the explanation ofthem might be looked for, and to design special apparatus to

test his conjectures. The observations thus made showed-

"That' wind.' in general was not what it is commonly assumed to be, i.e., air

I Minutes of Proceedings Inst. C.E., vol. cvii., Session 1801-92, p. 546.

6 'POLE ON CHICAGO CONFERENCE ON AERIAL NAYIGATION. [Selected

put in motion with an approximately uniform velocity in the same strata, but

that, considered in the narrowest practicable sections, wind was always not onlynot approximately uniform, but variable and irregular in its movements beyondanything which had been anticipated, so that it seemed probable "that the verysmallest part observable could not be treated as approximately homogeneous,but that even here there was an internal motion to be considered, distinct bothfrom that of. the whole body and from its immediate surroundings. It seemedto the writer to follow as a necessary consequence that there might be a potenti­ality of what may be called 'internal work' in the wind. On further studyit seemed to him that this internal work might conceivably be so utilized as tofurnish a power which should not only keep an inert body from falling, butcause it to rise."

The author gives particulars, with diagrams, of many obser­vations' on the wind, showing evidence of its complex nature,of its internal movements, and of the resulting potentiality ofits internal work; with special reference to their importantbearing on the science of aerodronomiee (from aEpo8pop.iw, to

traverse the air). One prominent feature was, that the higherthe absolute velocity of the wind the greater the relative:fluctuations which occur in it. In a high wind the air moves in a

tumultuous mass, the velocity being at one moment perhaps 40

miles an hour, then diminishing to an almost instantaneous calm,and then resuming.

The author does not enter on any inquiry as to the cause ofthese phenomena, but he considers that, admitting that the wind

is very elastic and frictionless, the incessant alterations are due to

past impulses and changes which are preserved in it, and which

die away with very considerable slowness. He then points out

examples of how these internal variations may be utilized by thebirds to produce such phenomena as those which dictated the

enquiry.He sums up the leading points of his memoir essentially

thus �-

1. The wind is not even an approximate uniform moving mass

of air, but consists of a succession of very brief pulsations of

varying amplitude, and, relatively to the mean movement of the

wind, these are of varying direction.2. Hence there is a potentiality of "internal work" in the wind,

and probably of a very great amount.

3 and 4. An inclined surface may thereby be sustained, or

even raised, or made to advance against the wind without expendi­ture of internal energy.

5. This is not only mechanically possible, but is realisable in

practice.Prof. Langley'S Paper was di.icussed at some length by many

Papers.] POLE ON CHICAGO CONFERENCE ON AERIAL NA.VIGATION. 7

eminent authorities, and his idea was practically supported by a

Paper on "Atmospheric Gusts," by A. F. Zahm.The irregularity of the structure, if one may use the expression,

of high winds had heretofore attracted the notice of observers,though in an imperfect way. In 1873, the Author of this Paperwas engaged with Mr. W. H.' Barlow on the investigation of a

large design for a bridge across the Forth, by Sir Thomas, Bouch,and as the wind-pressure was a very important point, it was

determined to apply to the Astronomer Royal, Sir George Airy, forinformation thereon. He kindly replied to the inquiries, and, as

his letter was subsequently published,' there is no impropriety in

giving the following extracts referring to the wind's action. Theletter is addressed to Mr. Barlow, and dated 9th April, 1873.

" We know that upon very limited surfaces and for very limited times, the

pressure of the wind does amount. sometimes to 40 lbs. per square foot, or inScotland probably to more. So far as I am 'aware, our positive knowledge, as

derived from instrumental record, goes no further. But in studying the

registers it is impossible not to see that those high pressures are momentary,and it seems most probable that they arise from some irregular whirlings of theail' which extend to no great distance; I should say, certainly to no distance

comparable with the dimensions of the proposed bridge'; and that the fairestestimate of the pressures on the entire bridge would be found by taking themean of the recorded pressures at one point of space for a moderate extent oftime, as representing the mean pressure upon a moderate extent of space at one

instant of time. Adopting this consideration, I think we may say that the

greatest wind-pressure to which.a plane surface like that of the bridge will be

subjected on its whole extent, is 10 lbs. per square foot."

Now here the venerable Astronomer Royal has clearly indicated,as the results of his official observations, two things in regard tothe wind-force and the wind-motion. First, that a certainmaximum pressure, at a given point, exists only for a" very limitedtime;" i.e., that the particular stream of air impinging on that

point is subject to great fluctuation of force or pressure, whichseems to be an idea similar to that expressed by Professor Langley.Then Sir George adds another item of knowledge, namely, thatthat maximum pressure extends only over a" very limited surface,"i.e, that the whole current must be considered as divided uplongitudinally into a number of small parallel streams, eachof which has or may have a different force, or rather a different

arrangement of forces from those immediately around it. To these

may be added a third irregularity, which anyone may see by

1 Report of the Court of Inquiry and Report of Mr. Rothery, upon thecircumstances attending the fall of a portion of the Tay Bridge _

on the 28th

December, 1879. Parliamentary Paper, 1880 [O-2,616J.

"8 POLE ON CHICAGO CONFERENCE ON AERIAL NAVIG.A.TION. [Selected

watching a vane in a high wind, namely, that the stream im­

pinging on any point is constantly varying in direction, causingthe vane to oscillate rapidly.

During the subsequent erection of the Forth Bridge, from 1882

'onwards, a series of elaborate experiments was made at its site,by Sir John Fowler and Sir Benjamin Baker, on the action of thewind. 1 They referred in' a great measure to the effect producedby it on the peculiar structure of the members of. the bridge, andthis portion of the investigation, though exceedingly interestingand instructive, need not be further dwelt on here. But the chiefresults illustrating the nature of the wind itself may be stated as

follows. There were three wind gauges or pressure boards; a largeone, 300 square feet in area, and two small ones each of I! squarefoot area. Sir Benjamin had anticipated that, contrary to the

opinion of many, the large board would show a smaller averagepressure per square foot than the small ones, and the results boreout fairly his anticipations, the effective pressure on the large and

heavy board averaging only about two-thirds of that indicated byan ordinary light anemometer. Two very heavy gales were

experienced in the winter of 1883-4, and during one of them thesmall gauge was reported as registering 65 lbs. per square foot,but this was found to be due largely to instrumental defects, and

by the large board it was shown as only 35 lbs. Sir Benjaminmakes the following remarks on the subject ;-

"l look upon the record of 65 lbs. therefore as valueless so far as regards thespecific maximum pressure attained during the great storm, but of considerablevalue 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. From the records generally, and from my own

watching of the movements of the three gauges, I have come to the conclusionthat uniform velocity and pressure in a wind, whether it may prevail or not at

cloud-heights, can never obtain near the surface of the earth or in the neigh­bourhood of any bridge or other structure capable of causing eddies. Unsteadymotion must be the rule in air as in water, and the threads of the currents

moving at the highest velocity will strike an obstruction successively ratherthan simultaneously, so that the mean pressure per square foot on a large area

must be less than that on a small surface from that cause alone, irrespective of

possible differences in the partial vacuum at the back of the planes."Sir Benjamin confirmed this opinion, by ingenious observations

and calculations on the angle at which a sailing vessel heeled over

during a strong broadside gale; the vessel kept steadily showing a

mean pressure of 12 1bs. only per square foot, while heavy local

1 "The Forth Bridge," by Sir Benjamin Baker, read at the Montrealmeeting of the British Association, 1884; Library lust. C.E., Tracts 4to. Vol. 93,No.4.

Papere.] POLE ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. 9

gusts of very small area struck different parts of her in a distinctlyrecognisable manner.

These observations, therefore, seem in some measure to anticipatethe conclusion of Professor Langley, that in a high wind the airmoves in a tumultuous and irregular mass, and that the higher the

general velocity the more violent are the fluctuations. But, of

course, his explanation of the peculiar nature and import of these

fluctuations, as showing" internal work," is entirely original.

To return to the Papers laid before the Conference. Another

general subject of great importance is that of motive power. This

applies to all classes of aerial machines, and has, therefore, alwayshad much attention; the aim being to combine the maximum of

efficiency with the minimum of weight. The imitation of the

ornithological motive apparatus has never been successful, and ithas only been in late years that the invention of the screw pro­peller, and the modern skill in mechanical construction, have

brought aerial navigation within the reach of practical engineeringscience.

The earliest promising efforts were made in Mr. Giffard's balloonof 1852 with a steam-engine and a screw. Mr. Dupuy de Lome,in 1872, used the power of men, with a great waste of weight. In

1881 the lightest efficient motor the Author could hear of, was a

steam-engine made by Mr. Thornycroft, weighing about 40 Ibs.

per horse-power, but great improvements have been made sincethat time. Mr. Chanute mentions an announcement by Mr. Maximthat" he has constructed two steam-engines of 300 HP. which, withthe engine proper, the boilers, pumps, generators, condensers andthe weight of water in the complete circulation, weigh but 8 lbs.to the horse-power." And that, whereas the coefficient of efficiencyin the earlier aerial screws was less than 35 per cent., the same

experiments had increased it to at least double.Mr. Hastings devotes much attention to the theoretical action of

. the aerial screw, showing it to be a very effectual and manageabledevice. In regard to the motive power, he considers that a heavierone than 15 lbs. per HP., including all that pertains to it, willnot answer. Gas-engines he believes unsuitable, but he thinksthat explosive-engines of some other kind may be applicable. Atthe same time, the steam-engine has great advantages and may'probably be made light enough to be efficient, and the hest fuel forit may probably be found to be oil. The water should be con­

densed, as proposed by the Author of this Paper in 1881. Mr.

Hastings thinks a kind of " steam-turbine" may prove the lightest

10 POLE .ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. [Selected

of motors, and this forms the subject of a special Paper byMr. Dow..

Mr. Hastings alludes to the use of electric-motors, as used in

France, and thinks that in the present state of knowledge theywould be the easiest of all to develop to the required point of

Iightness,Mr. H. O. Vogt, naval engineer of Oopenhagen, contributes an

article on " Air-Propellers," which might, he considers, be applied,not only to navigate the air but to the propulsion of boats on thewater.

Mr. Kress also recommends a peculiar kind of" elastic air-screw."

Among the other Papers on this branch of the subject is an

excellent one on "Anemometry," by S. P. Fergusson, of Bene Hill

Observatory.An elaborate set of notes on the "Materials of Aeronautic

Engineering," by Robert H. Thurston; particularly aims at theattainment of strength with light weight.

II. AVIATION.

This division refers to the imitation of bird flight by machinesheavier than the air, which have not only to propel themselves butto overcome the force of gravity, and it appears to have been

specially encouraged at the Conference, Mr. Chanute, in his open­ing address, says, "As to flying machines proper, which promisehigh speeds, we can say that the elements of an eventual success

have gradually accumulated during the past half century. The

argument which has been made that man cannot hope to float his

greater weight upon the air would seem not to be well founded.There has been real substantial advance within the last few years.".Mr. Hastings, his pupil, has discussed at much length the theoreticalviews affecting the various aspects of the problem.

Elaborate observations are given in several Papers respectingthe sailing and soaring flight of birds, on which the ideas of those

supporting aviation are modelled. There is also a general Paperon "J!""11ying Devices," and many notes are contributed on the

design of flying machines. But so far as this Conference is

concerned, although, thanks chiefly to Professor Langley, therehas been considerable advance in the general knowledge of the

principles connected with movements through the air, and althoughmention is occasionally made of considerable mechanical improve­ments in the general modes of obtaining light motive-power, there

appears no account of any complete solution of the problem.

Papers.] POLE ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. 11

III. BALLOONING.

This alternative form of aerial navigation has at least the

advantage over mechanical flight, that it has been already putin successful practice. But it is objected to as introducing an

element considered undignified and unworthy, namely, the evasionof the difficulty of gravity by the flotation. The" gas-bag," as

it is' termed, is viewed as having no precedent in the ornitho­

logical apparatus on which, it is argued, aerial locomotion shouldbe modelled.

Yet it requires but a little consideration to show how unfounded,and indeed how unreasonable, such an objection is. The aim isfor man to acquire the empire of the world of air, as he has

acquired the empire of the ocean. But how has he acquired thelatter? Not by imitating the fishes, but by introducing theidentical new and foreign element of artificial flotation by dis­

placement of the fluid to be commanded. The boat on the water

corresponds with the " gas-bag" in the air., and there is no

more sense in despising the latter, than there would be in

arguing for the abolition of boats, and the substitution of in­

geniously-contrived swimming machines! The boat is a legiti­mate result of the intellect of man in circumventing naturalobstacles, and so is the balloon.

Ballooning was not strongly encouraged at the Chicago Con­ference. Mr. Chanute mentions fairly enough the successful trialsin France, and their proposed extensions, with an expectation of

attaining a speed of about 25 miles an hour, which he saw no

reason to doubt; but he adds-

"The attainment of this moderate speed requires very large and therefore

very costly balloons, which carry very few passengers, and it is clear that whilesuch craft may be justified by the exigencies of war, they cannot compete com­

mercially with existing modes of transportation. . . . It is difficult to conceive

how, if they be made of sufficient size, ..• such enormous and frail craft can

be handled, housed, 01' operated, without peril of casualty or disaster."

He then alludes to the discoveries of Prof. Langley, which,he conceives, favour the alternative plan of mechanical flight,"a mode of transportation which so strongly appeals to the

imagination."Mr. Hastings follows in the same strain. After stating the

results of the French experiments, and adding that only one of thefour balloons started had been able to return to its starting-point,and that none of them was ever tried but once, he says-

"These facts arc rather discouraging to those who hope. 'to achieve aerial

12 POLE ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. [Selected

navigation through the means of a navigable balloon. If the French Govern­

ment, by the use of more money than the most enthusiastic company of pro­moters could hope to secure, and with presumably the best ability that it was

possible to obtain; ... if the French Government, with these advantages, andwith several years of diligent trial, was unable to achieve more than the verymoderate success stated, it would seem as if it were useless f01' others to

attempt to solve the problem in this way, and without Government aid."

He then explains the well-known relations between power and

velocity, which, as with steam-ships, require increase of size for

larger cargos and greater speeds, and he argues that the smallerresults of which the smaller machines are capable would makethem commercial failures. He concludes thus-

"It is evident, that if the navigable balloon is to be kept in 'commission' as

many hours in the day and as many days in the year as is the steamboat or

locomotive, the cost of maintenance will be ruinous. The income from a

navigable balloon must therefore be very considerable in order to meet its main­tenance. The character of the material of which it is constructed is so fragilethat the apparatus is extremely liable to accident; and, as compared with woodor iron, it is very short lived. Those capitalists, therefore, who may venturetheir money in a navigable balloon project, should calculate on large rates of

profit to compensate them for the risks of the business, and in any case should

expect to get their money back in a very few months 01' not at all."

Mr. Chanute was more favourable to the balloon in his lectureof 1890, when he described the past proceedings of the French

engineers, and discussed their views for the future. He pointedout difficulties, but added-

"These difficulties can all be surmounted, no doubt, including the remainingone, that large balloons will be costly, and that few can afford to experimentwith them."

And he summed up with the remark-

"It seems likely, therefore, that in the neal' future elongated balloons will bebuilt, which will be driven at 25 01' 30 or a few more miles per hour, which willbe able to sail about ou all but stormy days; but the cargoes carried in propor­tion to the size will be small, and to obtain speeds similar to those of expresstrains some other form of apparatus will have to be sought for."

In comparing the balloon speed with that of express trains, Mr.Chanute omitted to notice that when the balloon is fortunate

enough to go with the wind, its speed with regard to the earth

may be very considerable.After describing the rival plan ofmechanical flight, Mr. Chanute,

at the conclusion of the lecture, said-

"Success with aeroplanes, if it comes at all, is likely to be promoted by the

navigable balloon. It now seems not improbable that the course of develop­mout will consist, first in improvements of thc balloon, so as to enable it to stem

Papers.] POLE ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. 13

the winds most usually prevailing, and then in using. it to obtain the initialvelocities required to float aeroplanes. Once the stability of the latter is welldemonstrated, perhaps the gas-bag can be dispensed with altogether."

According to these views, one would think that more encourage­ment might have been offered to balloon improvement at theConference. It seems to be admitted by all competent judgesthat, in the "gas-bag" contrivance, as now made successfully"dirigible" at speeds greater than ordinary winds, the empire ofthe air has been essentially acquired. How it may be improved?what uses can be made of it? and what dividend it may be madeto yield to commercial people who embark capital in it? are

questions the answers to which mustwait for further development,as has been the case with all new inventions. Meanwhile, there

may be repeated the closing words of the first English account ofmodern aerial navigation, written twenty years ago, "At allevents a dirigible balloon is a thing actually in existence; a

flying machine is, at present, only an idea."

The other communications on this subject are as follows:-Mr. Myers desoribes his mode of manufacture of balloons for

hydrogen gas, and the effects of temperature in balloon voyages;giving also some experiments tried by him on different formsof balloons and methods of manceuvring.

Mr. Wood makes some comparison between "flotation" and

"aviation," giving' preference to the former..

Several communications refer to the use of the ordinaryballoon for explorations of the upper atmosphere and for generalmeteorology. One of these is by a well-known authority,Mr. de Fonvielle, and is of considerable value.

On the whole, it would hardly seem that any result of importancehas followed the Conference, except the publication of Professor

Langley's new theory of the internal work of the wind, which mayperhaps prove of utility hereafter. The meeting has, however,contributed to spread the knowledge of what has been done, and

may tend, therefore, to convince the public that the idea of aerial

navigation is not a delusion, but is worth serious study.The Institution of Oivil Engineers has not hesitated to circulate

this opinion, as may be judged from the following passage in the

opening address of the President,' on the 13th January, 1885:-

"Thel'e may undoubtedly be particular circumstances in which it [loco­motion by dirigible balloons] would be useful, such, for example, as tho

1 Minutes of Proceedings Inst. C.E., vol. lxxx., Session 1884-85, p. 27.

14 POLE ON CHICAGO CONFERENCE ON AERIAL NAVIGATION. [SelectedPavers.

exploration of new countries, or as the present Egyptian campaign. I stronglysuspect that if our lively neighbours, instead of ourselves, had been invadingthe Soudan, they would long before this have had a 'dirigible' balloon lookingdown into Khartoum."

It may be mentioned that several societies are now formed forthe purpose of· studying aerial navigation, among which are

the British Aeronautical Society; the Aerial Navigation Societyof France; the Aviation Society of Munich; the ImperialAeronautical Society of Russia, and the Aviation Society ofVienna. There is also a magazine published every other month

�in Berlin (now in its fourteenth year), entitled, Zeitschrift furLuftschiffalwt und Physik der Atmosphare.

UNIVERSITY OF CHICAGO

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