DOMINION* o\ER PHYSICAL NATURE 



467 



observation is then corrected for half then double its angle of elevation 

 the sun's known diameter. above the horizon. The actual eleva- 

 As the image of the sun is reflected tion above the horizon is thus readily- 

 first by the index mirror and from it obtained and may be used for calculat- 

 l o the silvered part of the horizon ing the latitude. 



MARINER'S SEXTANT. LAND SURVEYING SEXTANT. 



Illustrations and article by courtesy of the Keuffel & Esser Company, New York City. 



mirror, the rays which reach the eve 

 have undergone two successive reflec- 

 tions. Therefore, according to the 

 principle of the instrument, the angle 

 between the two mirrors will be just 

 one-half the angle between the sun and 

 the horizon. The arc is so graduated 

 that the desired angle may be read 

 directly upon it. 



It will be readily understood that 

 the sextant must be constructed and 

 used with great care, as a very slight 

 mistake in its graduations or in taking 

 the observation will cause an error of 

 several miles in the calculated location 

 of the observer. Of course, a fixed 

 star may be used for an observation 

 in the absence of the sun . 



On land, when the horizon is not 

 clearly defined, it is necessary to use 

 a contrivance known as an artificial 

 horizon. This device is made in two 

 forms. One is a plain reflecting sur- 

 face with a level vial and screws by 

 which it may be set exactly level. The 

 second and better kind, consists of an 

 oblong trough filled with mercury and 

 protected from the wind by a roof 

 having in either slope a plate of glass 

 with its two surfaces ground to per- 

 fectly parallel planes. The angle be- 

 tween the observed object and its re- 

 flected image seen in the mercury is 



Maud and the Aeroplane. 



Maud Muller, on a summer's day, 



Was in the meadow raking hay. 



She always had enjoyed good health, 



But had a hankering for wealth. 



Her cheeks were red, her eyes were brown; 



She longed to live in the far-off town. 



She wished she might be richly dressed, 



And circulate among the best. 



The judge came sailing up the lane, 



Upon his nice, new aeroplane. 



Below him he beheld the maid, 



And tried to stop, and swooped and swayed. 



He ripped a top rail from the fence, 



And talked as if he had no sense. 



The engine got beyond control, 



The judge lost his immortal soul. 



Maud stood there with a sickly grin, 



Until he hit her with a fin. 



"My Lord!" she yelled, and ducked away; 



The judge lit on a pile of hay. 



She hurried where the spring gushed up 



And filled her little old tin cup. 



At first she thought the judge was dead, 



But she splashed the water on his head. 



He looked upon his aeroplane 



And said some things that gave Maud pain. 



At last he rose, and with a frown 



He started for the distant town. 



Then, bringing himself to halt, 



He said, "This, girl, is all your fault. 



"If you had not been raking here, 



I'd have stayed in the atmosphere. 



"You've cost me dear and spoiled my sport; 



I'll fine you for contempt of court!" 



He then went onward up the lane, 



And Maud returned to work again. 



She gazed upon his wrecked machine 



And said, "Alas! what might have been! 



"Ah, well, in heaven we'll all have wings!" 



And not depend on such fool things!" 



— Chicago Record-Herald. 



