4910 THE ZooLocist—May, 1876. 
flourishing condition, the portion occupied by the terns having 
been more thickly tenanted last year than in any previous season, 
notwithstanding that it is within two miles of the centre of a manu- 
facturing town, and is illuminated during the night by the glare of 
sixteen blast-furnaces. 
W. ARTHUR DURNFORD. 
Roper Street, Barrow-in-Furness, 
Noles on the Structure of Aquariums. 
By W. A. Lioyp, Esq.* 
On the Ist of March, 1876, Mr. W. S. Kent read, at the Society 
of Arts, a paper on Aquaria, and I was invited by the Chairman, 
General Cotton, to join the discussion which followed the discourse, 
but I preferred to make my remarks in type, and I now will do so, 
having before me the paper (as printed in the ‘Journal of the Society 
of Arts’ for March 3rd), crowded with errors both of commission 
and omission, from end to end. 
Mr. Kent’s chief point seems to be his objection to the plan of 
aquarium construction which I have successfully pursued for many 
years, and which consists in using unchanged sea and fresh water, 
kept in constant circulation, between a series of show-tanks con- 
taining animals and plants exposed to light, and an underground 
dark cool reservoir, containing several times as much water as the 
collective capacity of the show-tanks, Mr. Kent maintaining that 
large dimensions in the reservoir are unnecessary, for reasons which 
he does not set forth. I therefore have now to describe why 
I believe and know they are requisite. 
The average temperature of the air of the British islands, as 
determined from observations made during about one hundred 
years, is about 48° F. This, however, does not express the true 
temperature in its great variations, which range from occasional 
extremes of 102° F. above zero, to 8° F. below it, thus giving so 
great a range as 110° F. Before me is a chart of British tempera- 
tures from the year 1771 to 1853, in which these variations are 
shown in zigzag lines, which Mr. Hugh Gordon has, in a very 
* Part of a reply—published in the ‘Journal of the Society of Arts,’ and com- 
municated to the ‘ Zoologist’ by the author—to a Lecture on ‘ The Structure and 
Management of Aquariums,” delivered by Mr. Kent at the Society of Arts, and 
noticed in the April number of this journal (S. S. 4853). 
