THE MADRAS AQUARIUM. 
623 
of tlioif size. Experience has shown this plan to labour under two great disabi- 
lities : the great size of the opening, approximately one-third of the entire rear 
wall space, admitted such an excessive amount of bright sunlight as killed the 
lighting of the side tanks, while the arrangements did not even permit of the 
fishes in the tank itself being seen to advantage — partly by reason of the too 
great depth allowed and partly to reflection of the sky and clouds ; in rainy 
weather the arrangement sometimes led also to the flooding of the floor of the 
aquarium hall. Accordingly when ‘ Fisheries ’ took charge, it was decided to 
abolish this outside tank, close in the greater part of the opening in the wall and 
raise the low parapet wall over which visitors used to lean to view the contents 
of the tank, sufficiently high to accommodate a number of table aquaria. These 
alterations have proved satiafactory. 
In tne centre of the hall is an ornamental open freshwater pond sunk in the 
floor, with a central fountain. Tables carrying small rectangular glass-sided 
aquaria are disposed about the room wherever they can be conveniently placed, 
while the two end walls are utilized for the display of typical collections of 
preserv’ed specimens illustrative of the range of marine animals, dry and in 
fluid, available in the zoological supply section of the Fisheries Department 
for educational purposes, such as for dissection in i)ractical zoological studies 
or for museum display. 
The ten large tanks are constructed of masonry. They measure 7 feet in 
length by 4 feet from back to front, with a depth of 3 feet. The partitions 
separating them are of Cuddapah slabs (thick slate). Originally the backs of 
all the tanks were lined with white glazed tiles ; this has the great advantage of 
affording no lodgment for particles of uneaten food and dirt, a consideration 
of the greatest moment in aquarium management, but it does not satisfy the 
aesthetic sense and for this reason a rockwork background has been provided 
in a number of the tanks. Each glass front consists of a plate glass sheet, one 
inch in thickness, measuring 6'- 6" in length by 3 feet wide. The lower edge 
and the ends are bedded against a cement-formed ledge in the masonry frame, 
and after being caulked carefully with putty, an inner ledge of cement is 
added on the inside of the tank, so forming with the one formed originally 
on the outside, a deep groove within which the edge of the glass plate is 
secured. The putty used is a mixture of red lead, white lead and litharge 
powder amalgamated with boiled linseed oil by means of thorough pounding. 
In fixing the glass in position, a thick bed of this putty, mingled with 
oakum to give body, is placed in the half groove on the bottom and 
tlie edge of the glass rested on this. The space up each end of the plate 
is then filled in and only when this is set is the inner ledge of cement 
placed in position. This latter must not come into contact with the 
back surface of the glass; a space of ^th inch must be left, to be filled ultimately 
with the special putty. The upper edge of the glass is held in position by an 
ornamental wooden cross bar ; above this the space between the masonry 
pillars, between the fronts of neighbouring tanks, is filled in with wooden Vene- 
tians, with a door in the centre to permit access to the tank in an emergency. 
The bottom of the tank is three feet from the floor, a height found to be very 
satisfactory. The higher of the two barrier rails in front of each tank is 3'-6" 
from the ground and this, at a distance of 2 feet 6 inches from the glass front 
of the tank, has also proved to be the correct height. 
The method of daylight illumination adopted is from overhead by means of a 
large square of glass let into the centre of the roof tiling above each tank, the 
roo ing being a continuation of that over one side of the outer span of the 
aquarium hall. For evening illumination, electric light pendants are employed, 
5 or 6 in each tank, with opal glass reflectors. When artificial lighting was 
first introduced bracket lights were used ; these proved unreliable, for the 
wiring was so subject to wetting and corrosion that short circuiting often occurred 
