The mode in which the depressions and disturbances of trade are produced (equally with its excited and exaggerated forms) may be reasonably suggested. The motive power in the activities of commerce is the feelings - mainly, the desire to amass wealth and the desire to avoid losses - and the feelings are undoubtedly affected in a marked degree by the nervous condition of the body: the spring of hope and energy produced by a bright sunny day is a familiar experience. Indeed, many scientists (including, if my memory be accurate, so practised a scientific thinker as Sir John Herschel) - and the hypothesis is strictly within the range of scientific conceptions - have suggested that the brain is a voltaic pile, and each of its pulsations a discharge of electricity through the frame, the sensations experienced by the hand from the beatings of the brain being similar to a voltaic shock. Hence a disturbance in the electric condition of the earth involves in many persons the form of nervous derangement known as a headache. A sense of vigorous energy issues from hopeful and sanguine feelings (resultant from the corporal condition), and manifests itself in activity of trade, while a dulness and despondency of spirits depress the courage, resourcefulness and enterprise on which enlarged trading depends. And these feelings become intensified beyond the range of their original cause when, as in trading, they embrace, from sympathy, a mass of minds. Nor must it be forgotten that the vigour of the human brain and frame - as the instrument of influence upon the feelings and resulting acts - is dependent ultimately, through varied forms of transformation of energy, upon the solar light and heat. Regarding then the established power of the nervous condition upon the feelings, the effect of external influences upon this physical state, and remembering that the feelings constitute the prime mover of our actions (the intellect being merely the discerner of the end which the feelings desire to grasp, and the deviser of the modes of reaching it), it would appear that the abnormal and periodic convulsions in the sun and his intermediate stages of quiescence are most likely to produce a corresponding modification of the nervous system and emotions of man, with relevant courses and intensities of activity, which find their successive expression in the circular variations of trade and finance.

Mr. R. A. Proctor has stated that Jevons placed the occurrence of commercial crises near to the period when solar spots were least in dimensions and fewest in number. I cannot discover such a proposition in any of the writings of the Professor, and, as Prof. Foxwell has noted, the contention of Jevons was simply the coincidence of the period of crises (as a phase in the regular cycle of trading features) with the term which comprehended a sun-spot circuit. I do not think that observations are yet sufficiently mature and minute to determine the question whether crises concur with a maximum or a minimum stage of maculation. I should be disposed on the whole, on various grounds to attach weight to the former view, when - in addition to reasonable conjectures upon the causes of crises as the expression of feelings conjoined with physical conditions - we find, for example, that prominent crises occurred in the years 1805, 1815, 1825, 1836-9 (in America in 1837), 1847 and 1857, while sun-spot maxima were attained in 1804-5, 1816, 1827-8, 1837-8, 1848-9 and 1860. But, as I have already remarked (while the synchronism of the two cycles has been fully established), the relation between any particular phase of trade and the coincident condition of solar activity is one which, fruitful of promise, demands extended observation, and, especially, analysis of the character of each crisis. The essential point, I repeat, is, not the incidence of a crisis with a maximum or a minimum of spots (which has not yet been determined), but the definitely-founded truth that the periodic course of trade is - with that fulness of precision of which an enquiry of this nature admits - practically identical with the interval between each returning stage of solar energy.

The definite demonstration, from facts, of a recurrent trading revolution with a period of between ten and eleven years, appears to me to furnish conclusive ground, as I have elsewhere suggested, for basing our estimates of the average value of securities upon the variations which they have exhibited during a term of that duration.