110 RULES FOR INVENTION. 



are acted upon their specific gravities j consequently, the farther they fall the 

 more'hkn g re ater will be their distance j on this principle a separation can 

 heavy ones. be effected. 

 Practical re- II. What is the best plan in theory ? First make a current 



the lightbo*. ° f a ' r *° r tlie & ra ' ,n to fal1 tnr ® u S n > as dee P as possible. Tlien 

 dies from the the lightest will be carried farthest and the separation be more 



gram by a complete at the end of the fall. Secondly, cause tliegrainj 

 current of air ; r }> to 



deep; but not with the chaff, &c. to fall in a narrow line across the current, 



wide, across that the light parts may meet no obstruction from the heavy 

 Let the grain ' n being carried forward. Thirdly, fix a moveable board 



&c fall iuto edgeways to separate between the good clean grain and light 



compartments . « . . , , ,, 7, . 



and use the gram &c. Fourthly cause the same blast to blow the grain 



same blast re- several times, and thereby effect a complete separation at one 



peatedly. 



r * operation. 



tice^Th" ' ll1 ' Is th5s iheov y m P r a ctice already, and what are the dig- 

 grain does not advantages of the common process ? We find that the common 



fall through a farmers' fans drop the grain in a line 15 inches wide, to fall 

 suitable r ° 



cavity; nor is through a current of air about 8 inches deep, (instead of falling 

 itcleanec at \ n a j-, ne x an j nc h wide through a current 3 feet deep) so that 

 one operation. . . * . . , , , , «. , 



it requires a very strong blast even to blow out the chair j but 



garlic, light grains, &c. cannot be got out, they meet with so 

 much obstruction from the heavy grain. It has to undergo 2 or. 

 3 operations ; so that the practice is found to be no way equal 

 to the theory j and appears absurd when tried by the scale of 

 reason. 



Plan of im- IV. The fourth step is to construct a fan to put the theory in 



provements. pra(:lice ^ t0 try lhe experiment*. 



Exp. m. Art Example III. The art of warming rooms by fire. 



of ic rminsr o -r r™ • i c r .. • u ■ 



<ip>ntm,hts. S.ep I. lhe principles of fire are too mysterious to be m- 



Nature of fire vestigated here j but the effects are, 



Effect**? 1 ?/ ' lst * ^ iie ^ ire rare ^ es Vne air in { ^° loom, which gives the 

 rarefies the air. sensation of heat or warmth. 



II. Causes part II. The warmest part being lightest, rises to the uppermost 

 toascemi; p art Q f ^ Q room> nuc \ w \\\ ascend through holes, (if there be 



any) into the room above, making it warmer than the one 



in which the fire is. 

 Iff. particu- III. If the chimney be warm, the air will fly up it n>st, 

 chimney/ leaving the room empty. The cold air will then rush in at all 

 which pro- crevices to supply its place which keeps the room cold. 



* This Machinery, with a large passage or channel, is useful to clean 

 feathers from dirt and heavy bodies. — W. N. 



