STEPPES 



5548 



STEREOPTICON 



tended science classes at the University of 

 Edinburgh. He assisted his father in railway 

 surveying and in 1824 went to South America 

 to take charge of mining operations. After a 

 prolonged absence he returned to England to 

 assist his father in the building of the locomo- 

 tive known as The Rocket, which won a prize 

 of 500 ($2,500) offered for the best railway 

 engine. He afterwards became chief engineer 

 on the construction of the first railway to enter 

 London, known then as the London & Bir- 

 mingham Railway. 



Robert Stephenson is, however, chiefly noted 

 for the engineering genius shown in the great 

 bridges and viaducts constructed by him. He 

 was the inventor of the tubular bridge, of which 

 the two most striking examples are those 

 across the River Conway and the Menai Straits 

 in Wales. He also introduced the use of tubu- 

 lar girders in the construction of iron bridges. 

 The high-level bridge at Newcastle and the 

 Victoria Bridge across the Saint Lawrence 

 River at Montreal rank among the most 

 notable of his engineering achievements. 



He began early to show indications of the 

 engineering genius inherited from his father, 

 but his taste led him into the field of construc- 

 tion of railways rather than into the making of 

 railway engines. He visited Germany, Swit- 

 zerland and many other parts of Europe, also 

 Canada, Egypt and India, for the purpose of 

 building railways in those countries. Taking 

 considerable interest in the political affairs of 

 his country, he was elected a member of Par- 

 liament for Whitby, Yorkshire. B.M.W. 



Consult Smiles' Lives of the Engineers. 



STEPPES, steps, the Russian name for the 

 extensive, treeless lands extending from South- 

 eastern Europe along the borders of the Cas- 

 pian Sea to the Altai Mountains in Central 

 Asia. As there is little moisture, farming with- 

 out irrigation is impossible, although just north- 

 west of this region lies the vast "black earth" 

 plain, the best agricultural section of Russia, 

 where enormous quantities of grain are raised. 

 During the spring, when the rains start the 

 grass growing, great herds of cattle, sheep and 

 horses may be seen grazing, but they are soon 

 led to better pasturage by the wandering tribes 

 of Tartars, for the summer droughts dry up 

 the lands. The great plains of Western North 

 America and the treeless plains, or pampas, of 

 Argentina are also steppes. 



STEREOPTICON, stereop'tikon, an appa- 

 ratus for projecting on a white surface a mag- 

 nified image of a picture. The principal parts 



of the apparatus are the lantern, or box for 

 enclosing the light, the condenser, the objective 

 and the light. The lantern box, which is usu- 

 ally made of sheet iron of the best quality, has 

 openings at the top and bottom to provide 



a 



A MODERN STEREOPTICON 

 (a) Enclosing lantern (d) Bellows for length- 

 (&) Lens and conden- ening or shorten- 



ser ing 



(c) Transparent slide (e) Combination of 



lenses 



(/) Screw to manipu- 

 late bellows 



thorough ventilation. A door on the side next 

 to the operator gives ready access to the light. 

 The condenser consists of a large, double-con- 

 vex lens (see LENS), or, more frequently, of 

 two plano-convex lenses with their curved sur- 

 faces facing each other. The purpose of the 

 condenser is to gather the rays of light and 

 throw them upon the picture to be projected. 

 The objective consists of two double-convex 

 lenses mounted in a tube of the right length to 

 enable each lens to aid in magnifying the pic- 

 ture. This tube is mounted in a frame with 

 a rack and pinion, enabling the operator so to 

 adjust the focus of the objective to the con- 

 denser as to get a sharp definition of the pic- 

 ture on the screen. 



The Light. Various devices are used for 

 illuminating stereopticon pictures. That in most 

 general use, and the most satisfactory where 

 large pictures are required, is the electric arc 

 light, in which the carbons are arranged at 

 right angles. This gives a strong, even white 

 light, but its manipulation requires some skill. 

 Single lanterns are on the market which use 

 an incandescent light that can be operated by 

 connecting it with an ordinary electric light 

 attachment. For use in small rooms requiring 

 a picture of medium size these lanterns are 

 very satisfactory. They can also be used with 

 a battery of dry cells and are well adapted to 

 schools and halls in rural communities. Acety- 

 lene gas and the oxyhydrogen limelight are 

 also in use, but they have virtually been re- 

 placed by the electric light because of its 

 greater convenience. 



