Orbits of M 007i ana Earth not Ellipses. 



469 



partial vacuum and a slow motion. This shows how much fluid motion in one 

 direction can influence pressure and motion in another. In Fig. 35, the 

 Injector, the friction of the steam against the metal raised the temperature o° - 17, 

 and the pressure I lb. above the pressure in the boiler, and yet made a partial 

 vacuum in an adjoining stratum of fluid, that is, in the water-pipe. This ex- 

 periment is a proof that the barometer cannot give a time indication of weight 

 when there is motion in the atmosphere. The Injector is a case strictly in 

 oi nt ; the currents of steam and water not being separated by any valves, 

 are true types of the contrary currents occupying adjoining strata in the 

 atmosphere. 



The drawing, Fig. 35, page 468, represents an ordinary injector. About 60 

 experiments were kindly made for me by James Cudworth, C.E., at Ashford, 

 to determine the state of the relative pressures in the boiler, injector, and 

 water-pipe as soon as the water began to enter the boiler. The currents 

 at different levels and different direction in the atmosphere may affect the 

 barometer much as different currents of steam when the boiler pressure change 

 very rapidly affects the reading of fhe'barometer. The results of the experi- 

 ments were that in passages connected with each other there was a difference 

 of 100 lbs. in pressure. The direction of motion of the fluid in one part of 

 the apparatus entirely modified pressure in another part. 



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SUN'S ATTRACTION. 



The question of the effect of the sun's heat on different parts of the earth no 

 doubt depends upon the angle at which the ray or heat-vibration from the sun 

 strikes each part of the earth ; but the question of the time and motion of each 

 square foot of the earth's surface is exposed to the sun's rays should also be taken 

 intoaccount. We knowthat theeffect of the chemical rays depends very much upon 



