420 SPECIAL RESULTS IN THE URANOLOGICAL 



to the employment of more exact corresponding measure- 

 ments; while at the same time a more widely prevailing 

 mathematical training has rendered observers less liable to 

 persuade themselves of the accord of uncertain observations 

 with a previously conceived theory. 



The progress of our knowledge respecting igneous me- 

 teors will be the more rapid the more impartially facts are 

 separated from opinions, so that while carefully sifting or 

 testing all alleged particular facts, on the one hand, we may 

 not, on the other, fall into the error of rejecting as bad or as 

 uncertain observations, whatever results we are not yet able 

 to explain. It appears to me most important to separate 

 physical relations, from those geometrical and numerical 

 relations which admit, generally speaking, of more certain 

 and assured investigation. To this latter class belong 

 altitude; velocity; unity or multiplicity of points of de- 

 parture where ' ' radiation" is recognised ; mean number of 

 igneous meteors, whether in sporadic or periodic phenomena, 

 reduced, in order to determine their frequency, to the same 

 standard of measure in time, magnitude, and form, all 

 being considered in connection with the seasons of the year, 

 and with hours, or intervals before and after midnight. The 

 investigation of both classes of circumstances or relations, 

 viz. the physical and the geometrical, will gradually lead to 

 one and the same object, i. e. to "genetic" considerations 

 on the true nature and character of these phsenomena. 



I have before pointed out that, generally speaking, our 

 communication with the regions of cosmical space is solely 

 through light- and heat-exciting undulations, and through 

 the mysterious forces of attraction, exerted by distant masses 

 or celestial bodies according to the quantity of their material 



