THE CONDUCTION OF RESEARCH 427 



the personnel required in the testing. For example let us consider 

 a wind tunnel balance for measuring three forces and three moments 

 on an airplane model. Ordinarily two men operate the balance, read- 

 ing two of the required quantities at a time. If it were a question of 

 time, the balance might be arranged to use six observers who would 

 read the six quantities simultaneously, but this would increase the 

 operating expenses. The next improvement would be an automatic 

 balancing arrangement so that one observer could record all six 

 quantities, but this would require a much more expensive balance. If 

 it was desired to reduce the labor still further, the work of several 

 draftsmen could be dispensed with by making the balance record and 

 plot all six quantities, a process that is actually quite simple to do, 

 but which would require still more additions to the balance. The 

 elaborateness of a piece of apparatus, then, will depend largely on how 

 much it will be used, for there would obviously be no use in building 

 an expensive and labor saving machine for a few experiments, nor 

 would it be economical to use a cheap and inconvenient machine for an 

 extended series of investigations. 



Another particular that should be kept in mind when designing ap- 

 paratus is a construction that will make the calculation of results simple 

 and convenient. It very often happens that a small change in an other- 

 wise excellent instrument will save days, and perhaps weeks of com- 

 putation. As an example of the importance of this, it may be stated 

 that in a certain investigation on an airplane in free flight, the data was 

 collected in less than ten hours of flying, but required the time of three 

 men for four months to work up the final results, and there are other 

 experiments where the ratio is even greater than this. 



The economy of having a well equipped research laboratory is soon 

 demonstrated by the saving in time and expense in setting up for an 

 experiment, and the older a laboratory is the more apparatus there is 

 accumulated from which to select. In any experimental work a large 

 junk pile is invaluable, and until this is collected, the true experimenter 

 cannot work efficiently. The laboratory should have a shop of its own, 

 or immediate access to one, equipped to do the class of work desired, 

 as the ability to easily get small parts constructed or alterations made 

 is of the greatest importance in the efficient conduction of research. 

 Nearly all classes of research require in some way the application of 

 photographic methods, so that a dark room is a valuable, sometimes a 

 necessary adjunct to the laboratory. 



With the construction of the apparatus completed, we come to the 

 actual carrying out of the research. The first thing to do is to set up 

 and try out the apparatus and to determine with what accuracy the 

 results may be depended upon. It is good policy, especially in ex- 

 tended experiments, to take plenty of time in the beginning to get all 



