248 INSECT WATEE TRESPASSERS. 



and the speed of rowing would be very much in- 

 creased. 



This is exactly what is done by the Water Boatman, 

 and I strongly recommend the reader to catch a few 

 specimens, put them in a glass vessel of water, and 

 watch the action of the rowing legs. The blade of the 

 oar in the insect is found in a fringe of very stiff hairs, 

 with a slight curve backwards. The joints of the leg 

 are so constituted, that the limb has only one set of 

 movements, which are almost exactly like those of a 

 human rower, and the effect is very remarkable. 



As the stroke is made by which the Water Boatman 

 is propelled, the bristly fringes are expanded, so as to 

 " catch " the water, in the language of oarsmen, while 

 their slight curve enables them to " hold " it to the 

 end of the stroke. No sooner is the stroke over, than 

 the leg gives a slight turn in the socket, and, as the 

 limb is thrown forward preparatory to another stroke, 

 the bristly blade collapses, the sharp edge of the leg 

 is turned towards the water, and so the insect is 

 enabled to send its legs forward with the slightest 

 possible friction against the water. 



Only one point more with regard to those natural 

 oars. My rowing readers will remember that the 

 grease-pot is part of the essential furniture of a boat, 

 and that the leather and "button" of the oar have 

 to be frequently lubricated. There are few things 

 which worry an oarsman so much, or which impedes 

 his progress more, than the want of grease. In the 

 first place, the friction is increased very greatly, entail- 

 ing much needless exertion; and in the next place, 

 the squeaking sound of each stroke is nearly as irri- 



