SCIENTIFIC PROBLEMS OF THE FUTURE. 669 



new departures iu this Hue is the motor which Mr. Hiram Maxim has 

 worked out for his flying- machine. I have had the privilege of inspect- 

 ing it, and can certify that, whatever be the merits or ultimate success 

 of the machine generally, it is a marvel of mechanical ingenuity, and 

 the motor especially develops an extraordinary and unprecedented 

 amount of power for weight carried. 



yide by side with tliis great increase of power iu the motors, and of 

 equal importance, perhaps, in its bearing on the general question, we 

 must next consider the great fall in the price of aluminium, together 

 with the progress which has been made in the study of its valuable 

 alloys, such as the alloy with about 5 per cent of copper. 



Within my recollection the price of aluminium has fallen from a guinea 

 to about 2 shillings the ounce weight. A very moderate further fall in 

 price — far less than the above great and recent fall of 90 per cent — and 

 a little further corresponding iirogress in the study of the nature and 

 properties of these alloys, will cause aluminium alloys to drive steel out 

 of the market for many important engineering purposes, such as the 

 construction of bridges of wide span. And the new metals will be of 

 cardinal importance to aerial navigation, as they are the material upon 

 which we must rely for the construction of the flying machines of the 

 future. 



The third direction in which very important i)rogress has been 

 achieved recently is the theoretical and practical study of the condi- 

 tions which govern the resistance of the air and determine the laws of 

 flight or locomotion, as well as of suspension therein. The resistance of 

 the air is the one all-sufilicieut fulcrum or basis on which every flying 

 machine must rely. In the investigation of its laws something has 

 been done by the study of the flight of birds and the analysis of the 

 results of instantaneous photographs of them, especially by modern 

 French writers. For the laws which govern the flight of birds must, 

 mutatis mutandis — that is, in principle — apply to all aerial locomotion. 

 Hence, in the last edition of the Encyclopedia Britannica we see prog- 

 ress on the subject. Thus we find therein an instructive table, showing 

 clearly that, contrary to many people's ideas upon the subject, the sus- 

 taining or wing area in all flying bodies in nature increases in a much 

 less proportion than the increased weight to be carried. For the swal- 

 low or the sparrow has a much less proportionate area of wing than the 

 fly, the gnat, or the beetle; and the vulture or wild swan a much less 

 area than the swallow. This is an important fundamental fact in aerial 

 navigation, as showing that the flying machine of the future can be 

 made of very moderate dimensions. But by far the most useful prog- 

 ress in this direction has been made by Professor Langley in his excel- 

 lent " Experiments in aerodynamics," wherein he may fairly be said to 

 have laid down, for the first time, a really sound and reliable scientific 

 basis for the study of aerial locomotion by a series of careful experi- 

 ments and well-reasoned deductions from them. We may note with 



