J 08 



RULES FOR INVENTION, 



Rule for in- 

 venting I. 

 Consider the 

 theory and 

 present prac- 

 tice of art. 



II. and what 

 in speculation 

 ■would be the 

 best plan of 

 operating : 



III. how far 

 and in what 

 respects the 

 present prac- 

 tice can be 

 improved : 



IV. make ex- 

 periments or 

 Trials of the 

 plans thus 



4 educed from 

 reasoning. 



Example. I. 

 Tin ashing of 

 grain. 



I. Pi inciples of 

 the nrt. To 

 disengage the 

 grain : by 

 beating or by 

 rubbing. 



II. Theory 

 apply force to 

 the heads only. 



HI. Present 

 practice. 



Thrashing 

 by men : 

 treading by 

 animal*. 

 Disadvantages. 

 I. The force is 

 employed on 

 the straw as 



Rule 



Step 1. Is to investigate the fundamental principles of the 

 theory, and the process of the art or manufacture we wish to 

 improve. 



II. To consider what is the best plan in theory that can be 

 deduced from, or founded on, these principles, to produce the 

 effect we desire. 



III. Consider whether the theory is already put in practice to 

 the best advantage, and what are the imperfections or dis- 

 advantages of the common process of the art, and whether they 

 can be evaded and the process improved 3 and wh3t plans are 

 most likely to succeed. 



IV. Make experiments in practice to try any plans that the 

 speculative reasonings may propose or lead to. Any ingenious 

 artist, taking the foregoing steps, will probably be led to im- 

 provement in his own art ; for we see by daily experience that 

 every art may be improved. It will, however, be in vain to 

 attempt improvements, unless the mind be freed from prejudice 

 in favour of established plans. 



Example 1. Suppose we take the art of thrashing grain. 



Then by the rule. 



-Step 1. What are the principles on which this art is founded ? 

 The grain is contained in a head on the top of the straw enclosed 

 in a husk, or chaff, that requires a force to break the hull, and 

 disengage it j which may be done either on the principle of 

 beating or of rubbing. 



II. What is the best plan in theory for effecting this? As 

 we find that it requires nearly equal force, and is all contained 

 in the head, which is much less in quantity than the straw, 

 theory directs the force to be regularly and uniformly applied 

 to the head only, which will require but little power, seeing 

 we can rub it out between our hands. 



III. How is this theory put in practice; and what are the 

 imperfections and disadvantages of the common process ? the 

 grain in the straw is laid on a plank floor, and beaten by men, 

 with flails ; or on the ground, and trod out by horses. 



The disadvantages are. 



1st. The force is in both cases applied equally to the straw, 

 as well as the head. 



