NATURAL THEOLOGY. 357 



In this example we also see the resources of art 

 anticipated. One grand operation of chemistry 

 is the making of phosphorus ; and it was thought 

 an ingenious device to make phosphoric matches 

 supply the place of lighted tapers. Now this very 

 thing is done in the body of the glow-worm. The 

 phosphorus is not only made, but kindled, and 

 caused to emit a steady and genial beam, for the 

 purpose which is here stated, and which I believe 

 to be the true one.''^ 



VI. Nor is the last the only instance that en- 

 tomology affords in which our discoveries, or 

 rather our projects, turn out to be imitations of 

 nature. Some years ago, a plan was suggested 

 of producing propulsion by reaction in this way: 

 by the force of a steam-engine, a stream of water 

 was to be shot out of the stern of a boat, the im- 

 pulse of which stream upon the water in the river 

 was to push the boat itself forw^ard ; it is in truth 



female glow-worm differs from ,the male only in being apterous ; 

 but apterous female insects are not unfrequent ; th.us many spe- 

 cies of moths have no wings. The two circumstances of the 

 sedentary habits of the female, and the males flying by night only, 

 seems to show the use of the light. See the next note. 



^ There exists some controversy among naturalists as to the 

 use of the glow-worm's light. The doubt has been chiefly raised 

 by the observation that the insect is luminous, though in an im- 

 perfect degree, when in the state in which it cannot propa£ate, as 

 mentioned in the last note ; and that other insects are attracted 

 by light as well as the male glow-worm. The preponderance of 

 the argument is decidedly in favour of the supposition adopted by 

 our author, and which is also the commonly received opinion. 

 The particulars of the discussion will be given in the Appendix. 



