36 
The President's Address. 
efficient instrument for using the doublet lenses introduced 
by the late Dr. Wollaston ; the two lower pairs of tliese he 
framed and figured for himself. This was followed by the pro- 
duction of a large-sized instrument^ capable of effecting all 
that the best microscopes of that period were able to do. At 
the turning-lathe and planing-machine he was a thorough 
workman^ and these instruments he had constructed on his 
own plans, and much of them by his own hands. He was the 
first to show the great importance of employing the latter for 
perfecting the instrument and economising labour. 
Mr. Jackson was one of the original members of our Society 
at its formation in 1840, and most of his various suggestions 
for the improvement of his favorite instrument have been 
laid before the members. 
The first of these was a paper " On Microscopic Measure- 
ment/^ read September 23d, 1840, and printed in the ^ Micro- 
scopic Journal,^ vol. i, p. 11 — a subject with which his name 
has become so intimately connected. 
In April, 1841, he described a portable candle-lamp for 
illumination by reflection, some observations on which will 
be found in the ' Microscopic Journal,^ vol. ii, p. 77. This 
was followed in November, 1847, by his paper on "The Eye- 
piece Micrometer," published in the ' Transactions of the 
Society,^ vol. ii, p. 134. 
The small but elegant little ruling-machine, which he con- 
structed for the division of these micrometers, is a most effi- 
cient arrangement, and although, I believe, never figured or 
described, yet he had no hesitation in exhibiting it to any 
person who was interested in such matters. 
It was about this period that he also constructed a very 
complete and serviceable cutting-machine for producing thin 
sections of woods, &c. 
In 1852 Mr. Jackson was elected President of this Society, 
and I am sure that the members will all bear witness with 
me in stating that he was at all times most active in advanc- 
ing^ the true interests of the Society. 
In conjunction with Dr. Carpenter, Dr. Lankester, and your 
President, he was appointed by the Council of the Society of 
Arts a member of the committee, to assist in awarding their 
premium for the best and cheapest microscopes. 
In May, 1857, he exhibited and described a new form of 
travelling microscope, four of which he has constructed as 
presents to various relatives. 
Soon after the process of photography on collodion had 
become practised, Mr. Jackson turned his attention, with his 
accustomed clear-headed assiduity, to this engaging branch of 
