342 Prof Keilhau on the Present State of Geolog^^, 



ence to ite mode of formation, place it in the same class with 

 the strata ; and if we see it bounded on all sides by the sedi- 

 mentary rocks, we cannot attribute to it an eruptive origin ; in 

 short, by means of this simple but correct mode of examining 

 the subject, both the hypotheses which are most frequently 

 brought forward would be rejected. In the same manner un- 

 doubtedly, every hastily adopted opinion as to the origin of 

 rocks would, by a complete knowledge of the facts of the 

 structure of our globe, be at once reduced to its true value. 

 But this is not all, for this perfect, this, so to speak, anato- 

 mical knowledge, would also afford many positive contributions 

 to an insight into the actual nature of the object, — to an under- 

 standing of the origin and cause of the phenomena presented. 

 It can admit of no doubt that geology would undergo very 

 essential changes, were we able in such a manner to have 

 an unobstructed view of the structure of the earth. So long 

 as, owing to the impossibility, in most cases, of obtaining 

 a knowledge of facts by direct examination alone, observers 

 always endeavour, in a greater or less degree, to assist their 

 observations by supposing, by means of considerations as to 

 causes and actions, how the phenomena under investigation 

 must be, this great evil must result, that the science does 

 not obtain possession of perfectly unmixed data. What are 

 termed facts frequently very little deserve the appellation. 

 Such data are partly the work of the understanding of the 

 observer, and, as they are more or less the result of a precon- 

 ceived explanation, the science becomes in the same degree 

 illusory, being founded on such a basis ; nay, the whole pro- 

 cedure remains a mere movement in a circle, inasmuch as the 

 observer explains what the explanatory reasoning itself has just 

 silently advanced. This great evil could not exist in the case 

 previously supposed. Imaginary relations would then never 

 take the place of those really observed, partly because there 

 would be no necessity for it, and partly because what was in- 

 accurate would be much too easily pointed out, and in this 

 way the mania for making hypotheses would be suppressed. 

 On the contrary, the opportunity afforded of furnishing the 

 science with that pure foundation of unfalsified data which it 

 now wants, would be eagerly embraced, and the first endeavour 



