1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



189 



dilations which are otherwise apprehended to ensue. With regard 

 to the former of these, there is no doubt the conception is just; but 

 a closer consideration shows it to be impracticable. We have no 

 hesitation in declaring that it would be absolutely impossible to con- 

 struct two planes of sufficient magnitude, sufficiently remote from 

 each other to allow them to be freely impinged upon, with sufficient 

 strength to maintain that position so completely as to form but one 

 object with reference to the power by which it is to be moved, con- 

 sistently with any thing like the lightness that would be necessary to 

 qualify it for the purposes of mechanical flight. With regard to the 

 second, if it is meant to propose as a model the plan, of which a 

 sketch is given in the number of the Mechanic's Magazine for the 

 8th of April, the same objection would apply. It would be quite im- 

 possible to construct it, or anything like it, of the proper size and 

 strength, within the limitation of weight required by the essential 

 conditions of the case. To which we would add, that we are inclined 

 to consider the provision itself uncalled for. If a plane could be con- 

 structed of any form sufficiently light and large to serve the purposes 

 of flight, it would be difficult to prevent it from assuming of itself a 

 form analogous to that proposed. But we are, moreover, sceptical as 

 to the properties ascribed to it, and the advantages which it is said to 

 hold out. The freedom from oscillation which bodies of that form 

 are stated to display in their progress through the air, and for the il- 

 lustration of which we are referred to the case of the shuttlecock, 

 we conceive arises partly from the additional distance of the centre 

 of gravity below the plane of suspension, (which its form obliges, but 

 does not restrict,) and partly from the diminished resistance it otters to 

 the descent; no very great recommendation, one would suppose, 

 where that propensity is the main difficulty to be overcome. But, in 

 truth, the simplest form in all these cases is the best; and if a circular 

 or elliptical surface cannot be made to answer the purpose required 

 of it, it will be in vain to seek for it in a more elaborate construction 

 or a more complex form. And thus much for the suspending plane. 



II. The next in order of the parts of Mr. Henson's aerial apparatus 

 which we have proposed to discuss, are the controlling appendages or 

 fan-like expansions, the purposes of which are, as we are given to 

 understand, to regulate the vertical and horizontal movements of the 

 machine, and present an obstacle to the oscillations to which it is ex- 

 pected to be subjected in its course. And first with respect to this 

 latter purpose, the appropriate instrument of which is a vertical wsb 

 of considerable superficial dimensions, extending from the front to the 

 back of the machine, bisecting the suspending plane, the mode by 

 which it is designed to operate is, we presume, by the resistance to 

 its displacement, which it would experience in the re-action of the 

 surrounding air. Now this resistance, be it observed, is entirely in- 

 dependent of the particular position of the resisting surface, and 

 ■would have been equally attainable, had it been horizontally instead 

 of vertically displayed ; in other words, had the projector, instead of 

 appropriating to that end a special instrument, made an equivalent 

 addition to the suspending plane. To this must be added, that by a 

 vertical arrangement, an opposition is afforded to the oscillations, 

 ■which tend to occur in one direction only; whereas, had the latter 

 alternative been adopted, all the oscillations which could occur would 

 have been equally provided against, while at the same time additional 

 efficacy would have been conferred upon that part of the machine 

 where it is most required. To have devoted a large, or any portion, 

 of his resources to the accomplishment of a single purpose, and that 

 of doubtful and secondary importance, when it might have been made 

 equally conducive to another, and that most exigent and essential, 

 argues a great neglect of economy in those particulars in which its 

 unqualified observance is absolutely necessary to success, and a disre- 

 gard, to say the least, of those principles upon which the operation 

 of the chief members of the machine depends. It is exactly as if a 

 person having only two horses, and a carriage which their united 

 efforts were but just sufficient to move, were to keep one of them 

 always in reserve, for the purpose of attaching it behind occasionally, 

 when the carriage was going down a hill. 



By the intervention of the second of these controlling appendages, 



we are likewise informed, is to be governed the ascent and descent of 

 the machine in its onward course, and the mode in which we are 

 given to understand this is to be effected, is by some disposition of it, 

 similar to that of the tail of a bird, enabling it to regulate within 

 certain limits the horizontal inclination of the suspending plane. 

 Now in respect of this, the least we can say is, that it is an expedient 

 equally unnecessary and inapplicable with the preceding. The posi- 

 tion of a plane suspended in equilibrio, is a matter so readily affected, 

 that he must have strange notions of the conditions of the case, who 

 conceives it necessary to make a provision for the purpose in an ex- 

 tensive and cumbrous apparatus. It is not in fact by any modification 

 of construction or application of special machinery that the object in 

 view is necessarily or properly to be accomplished ; but by a dispo- 

 sition of the appended weightequally simple and secure. A few 

 shovels full of coal thrown from the front to the back of the fire, or 

 the transfer of any of the aerial passengers from one part of the car 

 to another, would at any time effect a change in the position of the 

 whole floating mass, far more necessary, indeed, and difficult to guard 

 against than to accomplish; and from the smallness of the angle of 

 inclination, more than sufficient for the purposes which could ever in 

 that behalf be required. For it is not, in truth, by any such modifi- 

 cation of the position of the suspending plane that the ascent and 

 descent of the machine is to be properly governed, but by a modifi- 

 cation of the force with which it is propelled. The suspension of the 

 machine in transitu, being the result of the development of a certain 

 amount of resistance in the air opposed to gravitation, which resist- 

 ance varies with the rate, and consequently with the force under 

 which it is generated at a given angle, the conditions of this suspen- 

 sion, affecting the level of the machine's course, follow the exercise 

 of this power; so that having a force equal to the propulsion of the 

 machine at its highest elevation, its reduction to a lower level is the 

 natural and simple consequence of a reduction in the energy of the 

 force employed, and vice versa ; any modification in the obliquity of 

 the plane which might be necessary to second this movement, being 

 more than sufficiently attainable by the occasional disposition of the 

 appended weight as before explained. 



But the adoption of this device, sufficiently extravagant, even if 

 conceived with a just notion of its effects, becomes doubly preposte- 

 rous, when viewed in the light of a contrivance, not only unnecessary 

 and inapplicable to the purposes for which it was intended, but abso- 

 lutely producing its effects in direct contravention of the anticipated 

 results of its operations. For what are the consequences of the mo- 

 dification in the obliquity of the suspending plane, to be brought about 

 by the agency of this caudal appendage, as described by Mr. Henson, 

 in the specification of his machinery, and inconsiderately adopted by 

 all those, without exception, who have taken upon themselves the 

 office of enlightening the public upon this interesting subject '. To- 

 tally overlooking the circumstances upon which the actual suspension 

 of the machine depends, and regarding it as it were a body endowed 

 with the power of following with equal facility any course towards 

 which it might happen to be directed, all alike concur in considering 

 the disposition of the inclined plane as giving (so to speak) the cue 

 to the appended body ; so that having attained an elevation in the 

 bosom of the air, all that is necessary to increase that elevation is to 

 augment the angle of inclination, and, vice versii, to diminish the ele- 

 vation, it is only requisite to decrease the inclination of the sus- 

 pending plane. Now the whole of this reasoning is false, and the 

 consequences in fact directly contrary to what they are here repre- 

 sented. So far from the direction of the plane indicating and con- 

 trolling the course of the machine in the way described, paradoxical 

 as it may appear, the modifications in question would be productive of 

 exactly opposite results ; as will be evident to those who consider the 

 conditions upon which the support of the plane in transitu is really 

 dependent. The resistance developed upon the under surface of the 

 plane and resolved in a direction opposed to gravitation, which is the 

 true grounds of its support, following the ratio of the squares of the 

 sines into the cosines of the angles of inclination, while the horizontal 

 resistance, which is the measure of its propulsion, varies as the cubes 



