PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
87 
been discovered by its means, such as rubidium, caesium, I 
and thallium; and its application to the manufacture of 
steel by the Bessemer process had enabled us to obtain 
that important article of commerce in much abundance, 
and at a low price. 
As to the nature of light, two theories had been pro¬ 
pounded on this subject. One was that light consisted en¬ 
tirely of indefinitely small particles which were projected 
from the sun and other luminous bodies, in straight 
lines, in all directions, with incredible velocity. As it 
was supposed by this theory that a substance escaped 
from the luminous body, it was usually called the theory 
of emission or emanation, and sometimes the corpuscular 
theory. The second hypothesis was usually called the un- 
dulatory theory, according to which the universe was 
supposed to be filled by a very subtle substance called 
aether, which penetrated everywhere, and which we were 
unable to perceive so long as it remained at rest. A 
luminous body caused it to enter into undulations similar 
to those of the air when sonnd is produced. Both the un- 
dulatory theory and that of emission enabled us to explain 
the ordinary phenomena of optics, such as reflection, re¬ 
fraction, &c., and so far it was difficult to shew any superi¬ 
ority which the one had over the other; but when we pro¬ 
ceeded to diffraction, polarisation, &c., we were compelled 
to renounce the former and embrace the latter. He did 
not know of any one whose opinion was worth noticing 
who adhered to the theory of emission. 
January 4th, 1883. 
Mr Robert Pullar, F.R.S.E., Vice-President, in the 
Chair. 
NEW MEMBERS. 
Mr Samuel L. Condall, South Tay Street, and Mr 
Robert Keay, Assistant City-Clerk, were elected mem¬ 
bers; and Sir Robert Menzies of Menzies, Bart.; Rev. Mr 
Stevenson, Middle Church; Mr D. R. Irvine, Perth 
Brewery; Messrs James Bridges, Perthhire Advertiser; P. 
P. Carnegie; James Kaye, Balhousie School; William 
Barclay, Watergate School; and J. S. Cruickshank, were 
nominated for election. Dr Andrew Wilson, F.L.S., Edin. 
burgh, was nominated for election as a corresponding 
member. 
DONATIONS. 
The following donations were intimated:—Fox killed 
near Coupar-Angus, from Mrs Archibald Coates, Paisley; 
two black and two red grouse (male and female), from Sir 
Robert Menzies ; one blackbird (female), two red-wings 
(male and female), and a wasp’s nest, from Colonel Drum¬ 
mond Hay of Seggieden. 
AUDITORS. 
Mr Henry Coates and Mr Robert Keay were appointed 
auditors of the Treasurer’s accounts. 
The Secretary read the following obituary notice of the 
late Mr John Sadler, Curator of the Royal Botanic Gar¬ 
dens, Edinburgh, communicated by an old member of the 
Society:— 
John Sadler, curator of the Royal Botanic Gardens 
and Arboretum, Edinburgh, who died upon the 9th De¬ 
cember last, although born in Fifeshire, came at a very 
early age (when he was about a year old, I think) with 
his family to Moncreiffe, where his father had been ap¬ 
pointed gardener. His first education was received in 
Dumbarney Parish School, and latterly he attended the 
Seminaries, Perth. About the year 1854, his family re¬ 
moved to Edinburgh, and about that time, or shortly 
before, he was sent to Bristol, where he entered the 
employment of an uncle, a general merchant in that town, 
who, if I understood aright, was said to be the type from 
which Dr Smiles drew his character of the “Successful 
Merchant.” Mr Sadler’s engagement there appeared not 
to suit his tastes, for in a very short time he returned to 
Edinburgh, and entered the Botanic Gardens, where he 
remained till his death. He was then about 17 years of 
age. In this new sphere of life, he had the very best 
opportunities for cultivating his taste for botany, which had 
no doubt been early implanted in his mind, when in child, 
hood he was playing in the gardens and wandering through 
the woods of Moncreiffe. As assistant to the Professor of 
Botany, he was brought continually into contact with the 
various phases of botanical knowledge, from its most rudi¬ 
mentary stages to the most abstruse and complex questions; 
while his association with some of the most advanced 
students was the means of affording him the most recent, 
full, and accurate information in all the branches of his 
science. Although the sources of knowledge were thus so 
easily within his reach, and although the acquiring of it 
seemed to be more of the nature of a pastime to him than 
a hard study, he does not seem to have been content to 
take it all from second hand, for he was a shrewd observer, 
and was fortunate enough to contribute original matter 
by several new discoveries. It is more from his manner, 
