46 METHODS OF APPLICATION. Art. 40 



spent, while a blind attack results in failure and disappointment. 

 The simplest method is also usually the one requiring the least 

 work and is, for that reason, the safest. 



3. Keep all solutions in neat shape, avoiding confusion, 

 mistakes will be easier found and corrected. For this purpose it 

 is necessary to have always an extra sheet of scratch paper. 



4. Consider the reasonableness of the result. Even a be- 

 ginner will have some bounds beyond whch a result will appear 

 unreasonable, and with experience these bounds are very much 

 narrowed. See that results are in proper units. A force times 

 a distance can not equal pounds. 



5. Use no short cuts. Short cuts come with practice, but 

 with a beginner they lead to mistakes and useless work. 



6. Use some check. A check may consist of a rough in- 

 spection of the numerical operations, the determination of an 

 unknown by two different methods, a solution by another method, 

 a reversed solution, a comparison of various results, a comparison 

 with a solution of a similar problem, or a repetition of the work. 

 It is not a sin to err, but it is a sin to allow the error to remain 

 undiscovered, and sometimes the consequences may be serious. 



7. Avoid useless refinement. An error of 50 Ibs. in a stress, 

 as calculated from the assumed data, (for a bridge or a building) 

 is much to be preferred to having such stress expressed in odd 

 figures or fractions of a pound. Some judgment should be 

 brought to bear in such matters. 



8. For each unknown, decide upon a method of application 

 of the equations of equilibrium and adhere to it. The unknowns 

 are the magnitudes of reactions and stresses and sometimes also 

 the directions of the reactions. It is not necessary to adhere to 

 one method of application in a particular problem, but it is very 

 essential not to get them confused in getting a particular 

 unknown. 



The equations of equilibrium may be applied in six ways, 

 namely, algebraically 1 or graphically, 



1. TO THE STRUCTURE AS A WHOLE. 



2. TO ANY ONE JOINT. 



3. TO ANY PART OF THE STRUCTURE CUT 



OFF FROM THE REST. 



The first method considers the whole structure in equilibrium 



^'Analytically" is sometimes used in place of this term, but both 

 methods are analytic. 



