MEAN SCOTTISH METEOROLOGY. 283 



7. Temperature, Barometric Range, and Sun-Spots. 



Without any doubt the greatest similarity in that way will be found in the several 

 temperature returns ; and after scanning the projections of each kind of temperature by 

 itself, reference may be made to the composite Plate No. V. giving the mean curve 

 derivable from the mean shade temperature, the maximum shade temperature, and the 

 Black-bulb by day exposed thermometer. The characteristic outbreak being nearly as 

 distinct in the beginning of the presently existing, not yet terminated Sun-spot cycle, 

 as it was in either of the earlier cycles ; or for the dates now confirmed by the tempera- 

 ture observations, of 1856-7, 1868 and 1880. While of the last we may further point 

 attention to the exceedingly cold waves both before and after the hot wave. 



But all the Terrestrial elements of Meteorology need not be exactly similarly and 

 synchronously excited by Solar innate energy, when that is suddenly re-awakened at or just 

 before each of the above three dates. And accordingly the next most remarkable depen- 

 dence on a new Sun-spot beginning, but rather later than the temperature shock, say in 

 the years 1860, 1870 and 1881, is found, first in the projection of Barometric pressure, and 

 then and still more remarkably, in that of the Monthly range of that same kind of pressure. 



Now that is an important double result to have arrived at, because the Barometer is 

 the most accurate and dependable instrument which Meteorologists possess. It is one 

 too with which it is almost impossible to make a bad observation for this purpose ; one 

 where no prejudice can exist at the time of making the observation ; and where the 

 numbers chronicled refer to something invisible to the eye, imperceptible to the feelings, 

 and yet allowed already to be at the base and root of almost all Meteorology ; hardly 

 ever too suspected to be in cosmical alliance with Sun-spot cycle beginnings, by the actual 

 observers at the time. 



Yet look in these plates on the three Sun-spot cycle waves above, and the three groups 

 of pressure range undulations below ; both in the original simple Plate, I. ; and in the 

 composite Plate II., where the absolute Barometric Pressure is combined with three times 

 the value of the Monthly range thereof. And observe also how the third Sun-spot cycle, 

 is borne out just as well as either of its predecessors, if we take account of its greater 

 variation in shape from a standard Sun-spot cycle. 



8. Details of Sun- Spot Cycles. 



Now I have already hinted that even a Standard Sun-spot cycle, though forming a 

 very visible cyclical curve, is something much more complicated than the uniform revolu- 

 tion of a solid wheel. 



Every Sun-spot cycle for instance yet chronicled, has the front of its undulation 

 steeper than the rear ; testifying to the greater energy of the Solar radiations in that 

 earlier part of the cycle ; or when there is, mirabile olictu, more nearly a minimum, than 

 a maximum, of visible spot area. 



And every cycle yet chronicled testifies also to the occurrence of another, though 



