I 38 HOW TO WORK 



of drawing I have already spoken. Even sketches in outline are of 

 great value if the size of the object has been correctly registered. 

 Mere plans are of great use in many cases and supersede the neces- 

 sity of description. This subject has, however, been fully considered 

 already. See p. 26 to p. 35. 



Zlfi. Of Drawing Inferences from 'observations. No one en- 

 gaged- in the pursuit of any branch of natural science is more tempted 

 to be led into too hasty generalisation than the microscopical 

 observer. It is his duty, therefore, to avoid drawing inferences until 

 he has accumulated a vast number of facts to support the conclusions 

 at which he has arrived. True generalisations and correct inferences 

 promote the rapid advancement of scientific knowledge, for each new 

 inference may form the starting point of a fresh line of investigation ; 

 but on the other hand, every false statement, regarded as arr observed 

 fact, forms a terrible barrier to onward progress, since, before the 

 slightest useful advance can be made it is necessary to-- retrace our 

 steps, it may be for a long way, before we can hope to recommence 

 our onward course. Again, a much greater amount of evidence is 

 always required to overthrow a false conclusion than is sufficient to 

 propagate the original mistake ; and there can be no task more un- 

 satisfactory than that of being called upon to controvert the- opinions 

 and deductions of others. 



In this sort of enquiry I think it is a good plan not to make too 

 minute notes during, the progress of an investigation, but to retain, as 

 far as may be, the facts observed in the memory. When the whole 

 matter is made out, but not before, we may begin writing and record- 

 ing the observations. Otherwise, imperfectly observed facts are liable 

 to be set down as actual facts, and afterwards argued upon as if they 

 were truths. Thus the observer may gradually be led more and more 

 astray, until he ends by adopting a conclusion totally at variance with 

 the real truth. 



Scientific enquiry, ought continually to advance, and we should be 

 able to extend our researches from the point where they have been 

 left by our predecessors, adding successively to what they have dis- 

 covered ;. but the observations which we owe to them should require 

 little correction. In not a few instances must we feel the highest 

 respect for the careful observations of the older observers, and I fear 

 it must be reluctantly confessed, that many of our modern researches 

 are not carried out wish the same patience, painstaking industry, and 

 conscientious care as theirs* have been, and for this reason are likely 

 to be but short lived. Many recent observations urged with great 

 vehemence and purporting to depend upon actual demonstration, 

 have been set aside for others still more recent and, if possible, more 



