50 



KJiPOKT 1888. 



of St. Elmo's Fire it may be enough liere to say that they occur at 

 certain well-defined phases in the non-periodic fluctuations of atmospheric 

 pressure, temperature, humidity, changes of wind, and arrival from the 

 Atlantic of equally well-defined types of weather with their characteristic 

 cyclones. 



In addition to these researches and the preparation of the Ben Nevis 

 observations for the press Messrs. Omond and Rankin have been con- 

 ducting, as time and opportunity permitted, the investigations referred to 

 in last year's report. 



For the year 1887 the following were the monthly mean pressures 

 and temperatures, the hours of sunshine, the amounts of the rainfall, and 

 number of days without rain as recorded at the observatory, the mean 

 pressures at Fort Wilham being reduced to 32° and sea-level, those of 

 Ben Nevis Observatory to 32° only : — 



Jan. Feb. Marchl April I May I June July Aug. I Sept. Oct. I Nov. Dec. Year 



Ben NevisOb- 1 25-159 



servatory 

 Fort William 29-753 

 Difference . 4-594 



Ben Nevis Ob- 

 servatory 

 Fort William 

 DifEerence 



25-494 



30-128 

 4-634 



25-390 



30-433 

 4-643 



Mean Presmres in Inches. 



25-3751 25-472 



29-993 30-044 

 4-618 4-572 



25-680 



30-168 

 4-488 



25-426 



29-903 

 4-477 



25-424 



29-911 

 4-487 



25-359 



29-875 

 4-516 



25-445 



30-047 

 4-602 



26-086 



29-656 

 4-570 



25-089 



29-699 

 4-610 



Mean Temperatures. 



Rainfall in Inches. 



Ben Nevis Ob- 

 servatory 



Days of no 

 Hain 



Port William 



17-80 



7 



12-73 



13-30 

 12 



11-40 



6-90 

 14 

 3-50 



7-53 

 15 

 3-49 



3-97 



ir 



1-87 



7-51 

 18 

 3-23 



11-54 

 4 

 7-90 



8-71 



9 



3-03 



10-99 

 11 

 4-55 



12-19 

 8 



6-22 



8-99 

 9 



5-09 



17-58 

 4 

 8-18 



25-366 



29-934 

 4-568 



31-2 



46-2 

 15-0 



126-01 

 128 

 71-19 



Hours of Sunshine to nearest Whole Hours at Ben JVeris Observatory. 



No. of Hours I 23 I 56 

 Possible H"urs 231 264 



74 

 365 



120 

 426 



129 

 508 



206 

 529 



58 

 528 



57 

 467 



84 

 381 



32 

 319 



31 I 28 I 898 

 242 210 4,470 



For the year the mean temperature at Fort William was a degree 

 below the average, the greatest defects from the means being 3°-0 in 

 April, 2°-9 in December, 2°7 in October, and 2°-3 in March. On the 

 other hand, February was l°-6 above the average temperature of the 

 month, and June 2°-6. At the top of the Ben the mean temperature of 

 June was even relatively higher that at Fort William, being 45°-4, which 

 is the highest monthly mean hitherto observed. 



The minimum temperature on Ben Nevis for the year was 9°-0 on 

 March 12 at 2 a.m., which closely agrees with the minimum of previous 

 years. The maximum was 67"-0 on June 24, which is 7°-0 higher 

 than any previously recorded maximum. On seven days of this month 

 the temperature rose above 60°-0, and on September 20 a temperature 

 of 58°-8 was recorded. Indeed, an unusual occurrence of high tempera- 

 tures was an outstanding feature of the meteorology of Ben Nevis during 



the year. 



The registrations of the sunshine recorder showed 898 hours of sun- 

 shine during the year, the smallest number of hours, 23, occurred in 



