THE STUDY OF SOCIOLOGY. 7 



metallic gases, and the formation of a photosphere at that outer limit 

 where the gases condense; accepting the suggestion of Sir John 

 Herschel, so amply supported by evidence, that zones north and south 

 of the Sun's equator are subject to violent cyclones ; this hypothesis 

 is, that if a cyclone occurs within the atmosphere of metallic gases 

 between the molten sui'face and the photosphere, its vortex will be- 

 come a region of rarefaction, of refrigeration, and therefore of precipi- 

 tation. There will be formed in it a dense cloud extending- far down 

 toward the body of the sun, and obstructing the greater part of the 

 light radiating from below. Here we have an adequate cause for the 

 formation of an opaque vaporous mass a cause which also accounts 

 for the frequently-observed vortical motion ; for the greater blackness 

 of the central part of the umbra; for the formation of a penumbra 

 by the drawing in of the adjacent photosphere ; for the elongation of 

 the luminous masses forming the photosphere, and the turning of their 

 longer axes toward the centre of the spot ; and for the occasional drift- 

 ing of them over the spot toward the centre. Still, there is the diffi- 

 culty that vortical motion is by no means always observable ; and it 

 remains to be considered whether its non-visibility in many cases is 

 reconcilable with the hypothesis. At present none of the interpre- 

 tations can be regarded as established. 



Here are sundry suppositions which the man of science severally 

 tests by observations and necessary inferences. In this, as in other 

 cases, he rejects such as unquestionably disagree with unquestionable 

 truths. Continually excluding untenable hypotheses, he waits to de- 

 cide among the more tenable ones until further evidence discloses fur- 

 ther congruities or incongruities. Checking every statement of fact 

 and every conclusion drawn, he keeps his judgment suspended until 

 no anomaly remains unexplained. Not only is he thus careful to shut 

 out all possible error from inadequacy in the number and variety of 

 data, but he is careful to shut out all possible error caused by idiosyn- 

 crasy in himself. Though not perhaps in astronomical observations 

 such as those above implied, yet in all astronomical observations where 

 the element of time is important, he makes allowance for the intervals 

 occupied by his nervous actions. To fix the exact moment at which a 

 certain change occurred, his perception of it has to be corrected for 

 the "personal equation." As the speed of the nervous discharge 

 varies, according to the constitution, from thirty to ninety metres per 

 second, and is somewhat greater in summer than in winter ; and as, be- 

 tween seeing a change and registering it with the finger, there is an 

 interval which is thus appreciably different in different persons ; the 

 particular amount of this error in the particular observer has to be 

 taken into account. 



Suppose now, that, to a man of science, thus careful in testing all 

 possible hypotheses and excluding all possible sources of error, we put 

 a sociological question say, whether some proposed institution will 



