the dominion of the air-第2部分
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operly with the air ship we must conceive it WHOLLY submerged in the water and having no sail or other appendage projecting into the air； which would； of course； introduce other conditions。 If； however； a man were to sit astride of the log and begin to propel it so that it travels either faster or slower than the stream； then in that case； either by paddle or rudder； the log could be guided； and the same might be said of Lana's air boat if only he had thought of some adequate paddle； fan； or other propeller。 But he did not。 One further explanatory sentence may here be needed； for we hear of balloons which are capable of being guided to a small extent by sail and rudder。 In these cases； however； the rudder is a guide rope trailing on earth or sea； so introducing a fresh element and fresh conditions which are easy to explain。
Suppose a free balloon drifting down the wind to have a sail suddenly hoisted on one side； what happens？ The balloon will simply swing till this sail is in front； and thus continue its straightforward course。 Suppose； however； that as soon as the side sail is hoisted a trail rope is also dropped aft from a spar in the rigging。 The tendency of the sail to fly round in front is now checked by the dragging rope； and it is constrained to remain slanting at an angle on one side； at the same time the rate of the balloon is reduced by the dragging rope； so that it travels slower than the wind； which； now acting on its slant sail； imparts a certain sidelong motion much as it does in the case of a sailing boat。
Lana having in imagination built his ship； proceeds to make it float up into space； for which purpose he proposes four thin copper globes exhausted of air。 Had this last been his own idea we might have pardoned him。 We have； however； pointed out that it was not； and we must further point out that in copying his great predecessor he fails to see that he would lose enormous advantage by using four globes instead of one。 But； beyond all； he failed to see what the master genius of Bacon saw clearlythat his thin globes when exhausted must infallibly collapse by virtue of that very pressure of the air which he sought to make use of。
It cannot be too strongly insisted on that if the too much belauded speculations of Lana have any value at all it is that they throw into stronger contrast the wonderful insight of the philosopher who so long preceded him。 By sheer genius Bacon had foreseen that the emptied globe must be filled with SOMETHING； and for this something he suggests 〃ethereal air〃 or 〃liquid fire；〃 neither of which； we contend； were empty terms。 With Bacon's knowledge of experimental chemistry it is a question； and a most interesting one； whether he had not in his mind those two actual principles respectively of gas and air rarefied by heat on which we launch our balloons into space to…day。
Early progress in any art or science is commonly intermittent。 It was so in the story of aeronautics。 Advance was like that of the incoming tide； throwing an occasional wave far in front of its rising flood。 It was a phenomenal wave that bore Roger Bacon and left his mark on the sand where none other approached for centuries。 In those centuries men were either too priest…ridden to lend an ear to Science； or； like children； followed only the Will…o'…the…Wisp floating above the quagmire which held them fast。 They ran after the stone that was to turn all to gold； or the elixir that should conquer death； or the signs in the heavens that should foretell their destinies； and the taint of this may be traced even when the dark period that followed was clearing away。 Four hundred years after Roger's death； his illustrious namesake； Francis Bacon； was formulating his Inductive Philosophy； and with complete cock…sureness was teaching mankind all about everything。 Let us look at some of his utterances which may help to throw light on the way he regarded the problem we are dealing with。
〃It is reported；〃 Francis Bacon writes； 〃that the Leucacians in ancient time did use to precipitate a man from a high cliffe into the sea； tying about him； with strings； at some distance； many great fowles； and fixing unto his body divers feathers； spread； to breake the fall。 Certainly many birds of good wing （as Kites and the like） would beare up a good weight as they flie。 And spreading of feathers； thin and close； and in great breadth； will likewise beare up a great weight； being even laid without tilting upon the sides。 The further extension of this experiment of flying may be thought upon。〃
To say the least； this is hardly mechanical。 But let us next follow the philosopher into the domain of Physics。 Referring to a strange assertion； that 〃salt water will dissolve salt put into it in less time than fresh water will dissolve it；〃 he is at once ready with an explanation to fit the case。 〃The salt；〃 he says； 〃in the precedent water doth by similitude of substance draw the salt new put in unto it。〃 Again； in his finding； well water is warmer in winter than summer； and 〃the cause is the subterranean heat which shut close in （as in winter） is the more； but if it perspire （as it doth in summer） it is the less。〃 This was Bacon the Lord。 What a falling offfrom the experimentalist's point of viewfrom Bacon the Friar！ We can fancy him watching a falcon poised motionless in the sky； and reflecting on that problem which to this day fairly puzzles our ablest scientists； settling the matter in a sentence： 〃The cause is that feathers doe possess upward attractions。〃 During four hundred years preceding Lord Verulam philosophers would have flown by aid of a broomstick。 Bacon himself would have merely parried the problem with a platitude！
At any rate； physicists； even in the brilliant seventeenth century； made no material progress towards the navigation of the air； and thus presently let the simple mechanic step in before them。 Ere that century had closed something in the nature of flight had been accomplished。 It is exceedingly hard to arrive at actual fact； but it seems pretty clear that more than one individual； by starting from some eminence； could let himself fall into space and waft himself away for some distance with fair success and safety； It is stated that an English Monk； Elmerus； flew the space of a furlong from a tower in Spain； a feat of the same kind having been accomplished by another adventurer from the top of St。 Mark's at Venice。
In these attempts it would seem that the principle of the parachute was to some extent at least brought into play。 If also circumstantial accounts can be credited； it would appear that a working model of a flying machine was publicly exhibited by one John Muller before the Emperor Charles V。 at Nuremberg。 Whatever exaggeration or embellishment history may be guilty of it is pretty clear that some genuine attempts of a practical and not unsuccessful nature had been made here and there； and these prompted the flowery and visionary Bishop Wilkins already quoted to predict confidently that the day was approaching when it 〃would be as common for a man to call for his wings as for boots and spurs。〃
We have now to return to the 〃tame goose〃 method； which found its best and boldest exponent in a humble craftsman； by name Besnier； living at Sable； about the year 1678。 This mechanical genius was by trade a locksmith； and must have been possessed of sufficient skill to construct an efficient apparatus out of such materials as came to his hand； of the simplest possible design。 It may be compared to the earliest type of bicycle； the ancient 〃bone shaker；〃 now almost forgotten save by those who； like the writer； had experience of it on its first appearance。 Besnier's wings； as it would appear； were essentially a pair of double…bladed paddles and nothing more； roughly resembling the double…paddle of an old…fashioned canoe； only the blades were large； roughly rectangular； and curved or hollowed。 The operator would commence by standing erect and balancing these paddles； one on each shoulder； so that the hollows of the blades should be towards the ground。 The forward part of each paddle was then grasped by the hands； while the hinder part of each was connected to the corresponding leg。 This； presumably； would be effected after the arms had been raised vertically； the leg attachment being contrived in some way which experience would dictate。
The flyer was now fully equipped； and nothing remained for him save to mount some eminence and； throwing himself forward into space and assuming the position of a flying bird； to commence flapping and beating the air with a reciprocal motion。 First； he would buffet the air downwards with the left arm and right leg simultaneously； and while these recovered their position would strike with the right hand and left leg； and so on alternately。 With this crude method the enterprising inventor succeeded in raising himself by short stages from one height to another； reaching thus the top of a house； whence he could pass over others； or cross a river or the like。
The perfecting of his system became then simply a question of practice and experience； and had young athletes only been trained from early years to the new art it seems reasonable to suppo
