Monthly Calendar of Nature for Scotland. 379 



sun, and protected from falling moisture. The amount of evaporation is 

 what the air has exhaled from a watery surface, and can only show a pro- 

 portionate power of action on a surface nearly dry. 



The coldest day in April was the 3d : mean temperature of that day, 

 4r5°; extreme cold, 31° j wiad E. It may be remarked that the coldest 

 day in April, last year, was the 2d ; the extreme cold at that period was- 

 9° lower than on the 3d this year. 



The warmest day in April was the 30th ; extreme heat, 59° ; wind E. 

 A curious coincidence occurs in the highest temperature in the corre- 

 sponding months of this and last year happening on the same day, the 

 wind on both days of extreme cold and heat being in each case easterly. 

 The east blew from easterly points on 17 days, from westerly points on 

 8 days, and on 5 days it was variable. There were 9 days of brilliant and 

 3 of partial sunshine, the rest were cloudy. Peals of distant thunder 

 were heard on the 9th and 10th, followed by light showers. There were no 

 particularly loud winds throughout the month. 



The coldest days in May were the 6th and 7th : mean temperature of 

 these days, 41*5''; extreme cold, 31® j wind N. This frost was simul- 

 taneous throughout the island ; and, from the more forward state of vege- 

 tation in the south, it seems there to have done most damage. The warmest 

 day in May was the 31st : mean temperature of that day, 61°; extreme 

 heat, 72" ; wind S.E. The wind blew from the E. and S.E. on 20 days, 

 from the N. on 4 days, from the W. on 5 days, on 2 days it was variable. 

 There were 23 days of brilliant sunshine, an unusual occurrence in our 

 northern latitude ; 2 days of partial sunshine ; and- on 6 days the atmo- 

 sphere was cloudy. 



The larch was in leaf on the 5th of April, three days earlier than last 

 season j but the crown imperial, which flowered last year on the 9th, did 

 not blow this year till the 10th. The hawthorn was in leaf on the 12th; 

 the O'xalis Acetosella on the 17th, on the same day as in the correspond- 

 ing month last year. The maple tree was in leaf on the 28th. It may be 

 proper to remark, that in the leafing of trees there is often from 6 to 8 

 days' difference in trees unfolding their leaves, although belonging to the 

 same species, and apparently under the same circumstances : this is most 

 conspicuous in the beech, maple, ash, and oak ; the same plant uniformly 

 exhibiting the same appearance as to time of leafing every season. Those 

 from which observations in the register are taken are the same plants 

 every year, are neither the latest nor most forward varieties, and conse- 

 quently show the mean time of the species coming in leaf. Oats that 

 were sown in Annat Park on the 8th, appeared above ground on the 23d ; 

 a period of 15 days: mean temperature of that period, 48'6°. Oats sown 

 in the same park last season gave a braird in 17 days, under a mean tem- 

 perature of 47°. The difference of 1*6' of elevated temperature gave a 

 breard earlier by 2 days. 



The horsechestnut was in leaf on the 28th ; barley sown at Annat 

 Park on the 16th gave a braird on the 26th, being a period of 12 days; 

 mean temperature of that period, 49°. A temperature of 52° gave a braird 

 of barley at the same park last year in 9 days : difference of temperature, 

 3° ; and of brairding, 3 days. The birch tree was in leaf on the 30th. 

 The Scotch damsels of the olden time expected always to have a flower or 

 nosegay composed of the fragrant leaves of this native plant, to carry to 

 the " kirk" on the first Sabbath of May. Severe frost in the early part of 

 May gave a partial check to vegetation. On the evenings of the 6th and 

 7th georginas were killed down to the ground. The cuckoo was heard 

 for the first time on the 8th ; we never hear him in this part of Scotland 

 nowadays in April, although many of our popular traditions for that 

 month are connected with his cry. By the English papers it appears he 

 regularly makes his voice sooner heard in England. Rain and a thunder 



