380 USES OF WATER TELESCOPES. 



observer to see from three to twenty fathoms on cahn 

 bright days. Of course when the water is thick the 

 glass is useless. The Cornishmen, especially at the 

 Lands End, use these instruments for looking for nets, 

 lost crab and lobster pots, &c. 



In the Museum of the Royal Artillery, Woolwich, is 

 a model of a water-glass consisting of a square box of 

 wood, six inches each way ; a round piece of glass 

 somewhat larger than a watch-glass is let into the top 

 and the bottom of the box is formed by a square of 

 glass let into the wood about one foot square ; the inside 

 of the box is blackened. 



This model is exhibited by Captain Fred., Robertson, 

 R.A., who, ux^on a label close to the model, has placed 

 the follow^ing information : — 



'' At Halifax, Nova Scotia, I was ordered to weigh a 

 241b. gun, which had fallen into six fathoms of water. 

 By means of a water-glass, I was enabled to see its 

 exact position at the bottom. I then got a gunner to 

 dive, with an iron bar, which, with a rope attached, he 

 inserted into the muzzle of the gun. I then passed a 

 running-noose over the rope attached to the iron bar 

 fixed in the bore. The diver then passed the rope under 

 the gun until the noose was before one trunnion and 

 behind the other. The gun was then brought to the 

 surfac^ by means of a capstan." 



To the naturalist water telescopes will be invaluable, 

 as by means of them the actions of the fishes and other 

 inhabitants of the ocean can be observed better than in 

 any aquaria. The beauties and luxurious growth of 

 the submarine forests of sea x^lants will also to many 

 be a most novel and interesting spectacle. To water 

 parties who picnic on rivers or near lakes the water 

 telescope will be found a great adjunct to the day's en- 



