MEAN SCOTTISH METEOROLOGY. * 269 



This distribution, and these component numbers have not been always kept up exactly 

 every year, notwithstanding the best efforts of the Scottish Meteorological Society so to 

 do. But it is hoped they have always been preserved sufficiently near in Geographical 

 harmony, to prevent the final Meteorological Means being seriously perverted. Wherefore 

 the tables now presented, though sometimes of only 50, in place of 55, stations, may yet 

 be regarded with approximation as equally distributed about the country's central position. 

 While of the original 55, no less than 31 have continued identical in place throughout 

 the period from at least 1867 to 1887: though with 19 changes of observers amongst 

 them. 



2. Of the Old Tables newly continued to the Present Time. 



Table I. contains that necessary feature for all Meteorology, the mean monthly Baro- 

 metric Pressure for each month, of each year, reduced according to order and precedent 

 both to the temperature of 32° F., and to the sea level. The pressure is given in terms 

 of British Inches, and amounts on the means of all the months and all the years to 

 29*846. But with an evident annual cycle having a Max. in May and June = 29'929, 

 and a rain, in December and January = 29 '7 6 4 inches. 



Table II. contains the Mean Monthly range of Barometric Pressure for all the stations, 

 and amounts to 1*290 inch on the mean of everything. But with an annual cycle having 

 a Max. in the beginning of January = 1*6/1, and a min. in July = 0*897 inch. 



Table III. is the biologically, botanically, and commercially important return of Mean 

 Monthly Temperature of day and night, strictly in the shade, in degrees Fahrenheit, and 

 amounts on the mean of all the months and all the years to 46° '2 F. But with an 

 annual cycle having a Max. towards the end of July=57°"4, and a min. in January = 

 37°*0 F. 



Table IV. is the almost equally important Mean daily range in each month of that 

 shade-temperature; and amounts for a mean month of the whole year to 12°*5 F. Of 

 which quantity, if half be first added to, and then subtracted from, the previous 46°*2, 

 we shall have the highest and the lowest shade-temperatures in the cycle of a mean day 

 of an annual average kind. See also the new Tables XXI. and XXII. But of such daily 

 range there is an annual cycle ; whereof the Max. occurs in June = 15° '6, and the min. in 

 the beginning of Januarys 9° '1 F. 



Table V. advances from Shaded to Exposed Temperatures, and by means of Black-bulb 

 thermometers; of not always identical kinds, unfortunately; but for reasons stated on the 

 back of the Observer's printed Schedules by the Secretary of the Society. This Table V. 

 then gives the mean of all the daily readings for each month, or the mean of the highest 

 points reached every day in each month, at all the stations, by their Black-bulb thermo- 

 meters, fully exposed, nominally to the Sun, really to the sky, but by day alone. It is 

 therefore a very peculiar kind of thermometer reading, and claims for Scotland an 

 average, on the mean of all the days of all the months, of all the years and all the stations, 

 so high as 70°*5 F.; including therefore without doubt some 18° of Solar radiation as well 



VOL. XXXV. PART 3. 2 Z 



