282 PROFESSOR C. PIAZZI SMYTH ON 



Moreover it was then abundantly proved, that the chief manifestations of terrestrial 

 temperature were by no means simultaneous with the greatest tabulated areas of Sun- 

 spotted surface ; but were on the contrary singularly coincident with something that 

 rapidly took place in the Sun, during the first or second year only, or near the very 

 beginning of each 1 1 year cycle of spot making and growing ; and that this peculiarity 

 was borne out through a series of 5 of the cycles at least. 



Such manifestation too of extra temperature as then occurred on the earth, was not 

 a long continued, broad and quiet existency, — but more like the acute crest of a sudden 

 wave, followed always, and preceded too, within a year or two, by abnormally low hollows ; 

 or, so to speak, waves of cold. But all of them testifying to a violent variation of the 

 Solar radiating energy, occurring at or near the beginning of each Sun-spot cycle, and 

 being the one chief phenomenon of potency, to be recognised if possible, in each succes- 

 sive 1 1 years, more or less, period. 



Now has that triple phenomenon failed of late years ? 



The unprecedentedly large number of the Scottish Meteorologic observations at 

 present under discussion, eminently declare that it has not ! 



But how is such a point supposed to be proved ? 



In the present imperfect state of any Solar-physical theory, no dependence can be 

 placed on any expectation of what future Sun-spot periods are to be. We can only 

 trust actual observations of what they are, or have been. My first proceeding therefore 

 on the present occasion was to obtain the observed number of new spots in each 

 year, from 1856 to 1887. The first 22 years of that interval were supplied from 

 the plate in the XXIXth Vol. of the Eoy. Soc. Edin. Transactions, and the last ten 

 years have been kindly furnished to me by Mr G. M. Whipple, from observations 

 carried on, under his superintendence, at the Kew Observatory, in continuation of those 

 of M. Schvvabe, the first discoverer of any kind of periodicity in the Sun-spots. 



All these observations being duly projected for nnmbers and time, form three very 

 distinct undulations. The third and last is indeed not yet completed, and will not be 

 probably until 1890; but the limits of uncertainty in the shape of that part of the wave, 

 are far too small to influence the whole result from 1856 to 1887 — which is the full time- 

 range of the Meteorological Observations they are to be compared against. 



At the top therefore of each of our 1 4 Plates I have repeated those three, or to be 

 accurate 2 and ^, Sun-spot waves ; and beneath them, for simultaneous times, have pro- 

 jected the chief of this historic series of Scottish Meteorologic Observation Tables, as now 

 presented to Royal Society, Edinburgh. And on looking through all these faithful 

 Plates, in which do we find most, if any, approach to the Sun-spot cycle deduction just 

 described; that is, in the testimony to a starting of a new set of undulations in the first 

 or second year of each such cycle ; i.e., in the years 1856-7, 1868 and 9, and 1880 ? 



