USEFUL AETS. 



CHAPTER XIII. 



TELESCOPIC TUBES. DIRECT ACTION. DISTRIBUTION OP 

 WEIGHT. TREE-CLIMBING. THE WHEEL. 



Telescopic Tubes, their Structure and Uses. The Japanese Fishing-rod. The 

 Tripod Wheel-hearer and its Telescopic Structure. The Rat-tailed Maggot. 

 Locomotion. Direct Action. The Rocket, the Water Tourniquet, and 

 Electric Tourniquet. Cuttle-fish. The Flying Squids. The Paper Nau- 

 tilus. Proceedings of newly-hatched Calamaries. Larva of the Dragon- 

 . fly. Distribution of Weight. The Snow-shoe, its Structure and Mode of 

 using it. The Skidor of Norway. A formidable Rifle Corps. The Mud- 

 patten. Foot of Duck tribe. Foot of Jacana. Locomotion of Water- 

 gnat. Tree-climbing. Mode of ascending Palm-trees. The Value of a 

 Hoop. The "Girt Pupa" and Butterfly. Principle of the Wheel. The 

 primitive Wooden Wheel. Spoked Wheels. Driving Wheel of the Bicycle. 

 Naturally spoked Wheel of the Chirodota. 



MEANS AND APPLIANCES (continued). 



WE will now treat rather more in detail the two subjects 

 which were lightly touched upon at the end of the last 

 chapter. 



The reader will remember that the diamond-headed borer 

 is made in telescope form, so as to be adjustable at pleasure. 

 It was also remarked that the ovipositor of the Gad-fly was 

 made in a similar fashion, so as to be withdrawn within the 

 body of the insect when not needed, and protrusible to a con- 

 siderable extent when the Gad-fly wishes to deposit her eggs. 



As to our modern telescopes and opera- glasses, they are so 

 familiar that there is little use in describiag them, except to 

 say that their framework consists of a number of tubes of gra- 

 dually lessening diameter, the one sliding within the other, so 

 that the instrument can be lengthened or shortened at will, so 

 as to suit the focus of the observing eye. 



A very ingenious adaptation of the telescopic principle is 

 eeen in the Japanese fishing-rod, which is now tolerably well 



