3. The sky must be free from clouds.

4. The substances on which the dew is deposited, must be freely exposed to the action of the sky, and must be of such a nature as to radiate heat easily and to conduct it with difficulty.-Saturday Magazine.

THE BRIGHTON AQUARIUM.

A VERY decided addition to the attractions of Brighton is furnished by the new Marine Aquarium, which was lately opened to the public after having been three years in process of construction.

On passing through the gates the visitor arrives at the top of a flight of granite steps, 20 feet in width, which lead to an entrance court 60 feet by 40 feet. The front elevation of the building, facing this court, is 18 feet high, and consists of fine brick arches with terracotta columns and enrichments. A frieze running round the court bears the inscription, "And God said, Let the waters bring forth abundantly the moving creature :hat hath life." On the north side of the court is a commodious restaurant, and on the south side, which abuts upon the new road, the wall is broken by niches containing vases. From the court, the entrance-hall, which measures 80 feet by 45 feet, is entered by three doors. To the south of this hall here is another entrance, with an inclined plane instead of steps, for the admission of wheeled chairs. On the north side are the retiring rooms, kitchen, and other offices; and on the east side is the entrance to No. 1 corridor of the Aquarium proper. This corridor, the longest of the three, is 220 feet long, and is broken by a central hall 55 feet by 44 feet. roof, which is groined and constructed of variegated bricks, rests upon columns of Bath stone, polished serpentine marble, and Aberdeen granite, the capitals of the columns being carved in appropriate marine subjects. The floor is paved with coloured tiles arranged in a simple pattern. On either side are placed the first series of tanks, twenty-eight in number, varying from

The

55 feet by 30 feet to 20 feet by 11 feet 6 inches; the longest tank, which is upwards of 100 feet in length, being on the northern side of the central hall.

At the northern end is the Conservatory, 160 feet long by 40 feet wide, and 30 feet in height; the sides are covered with ornamental rock-work, set with ferns and other plants. At the extreme end of the Conservatory is a stream of water intended to illustrate the breeding of salmon and other fresh-water fish. On the southern side, running parallel with corridor No. 3, is а considerable space devoted to small table tanks.

From the southern end of corridor No. 2 runs No. 3 corridor. This corridor, which runs parallel with the Conservatory, is of the same length, and 27 feet wide; along its entire southern or seaward side is placed a line of tanks, intended for anemones and animals of that class, but at present containing store fish. Along that portion of the northern side not occupied by the table tanks are placed fresh-water tanks. At the end of this corridor, on the south side, there is a naturalist's room fitted with all necessary appliances; and on the north side there are the engines and pumps required for supplying the water, and for keeping it constantly aërated. The salt water is pumped direct from the sea into receiving tanks constructed under the floors of the corridors, and from these is conveyed into the smaller tanks and kept in circulation there by the same engine power. These tanks are capable of holding 500,000 gallons of water, and this quantity can be pumped from the sea in about ten hours. The same water can be used without renewal for an indefinite time; but it is absolutely necessary that it should be kept constantly supplied with air. In the open sea the air is perpetually renewed by the motion of the waves, but in a tank it would soon be exhausted by the respiration of the fish, unless there were ample provision for an artificial supply. This is effected by an air-pump, worked by steam power in the machine room, and connected with delivery pipes which descend nearly to the bottom of every tank.

The general effect of the Aquarium is extremely pleasing. Each corridor bears some resemblance to a picture gallery, in which the glass fronts of the tanks represent framed pictures. The subdued light, the rich, sober, and harmonious colouring, the plash of the waterfall, the freshness of the fernery, and the endless variety and grace of movement of the finny captives, combined to produce a scene of beauty and attractiveness, which called forth the warmest expressions of admiration from all who saw it, and on which those who formed it may be most cordially congratulated.

When the tanks were first filled, great anxiety was occasioned by frequent breakages of the glass fronts. These are made of plate glass, about one inch in thickness, and 74 inches by 40 inches surface measurement. It was supposed that they would be strong enough to bear any pressure to which they could be subjected; but it was found in practice that they would now and then suddenly split in every direction, permitting the water to escape and the fish, if not speedily rescued, to perish. It soon became apparent that these breakages did not depend upon direct pressure, since they would sometimes commence near the top of a plate, where the pressure would be least. Many reasons were suggested in order to account for them, and, among others, it was supposed that the two surfaces of a plate might be unequally expanded from difference of temperature between the air on one side and the water on the other. Quite lately it has been determined to bed all new plates in India rubber, and up to this time none of those so treated have given way.

Two varieties of dog-fish are included in the collection. One kind, which is mottled with dark spots, is of nocturnal habits, and remains motionless during most of the day. One of the females has deposited two eggs in the tank; and these, as well as two eggs which have been brought in adhering to a piece of seaweed, will be watched with great interest. The other dogfishes have no marking, and are in constant movement. The giant, whose untimely decease is mourned, belonged

to the latter family. Gray mullet, Atherine smelts, gurnards in every variety of colour, lobsters, cray-fish, and spider-crabs comprise the most noteworthy of the remaining inhabitants, and in almost every tank there are hermit-crabs, to do duty as scavengers. The death

of a small dog-fish afforded an opportunity of observing how well they discharge this duty; for it had scarcely reached the bottom of the tank when the crabs were seen moving towards it in all directions, and in an incredibly short space of time every morsel had disappeared before their united efforts. The lobsters have recently changed their skins, and are in the full glory of their most brilliant markings. Two of them seemed quite conscious of this fact, and spread out their beautiful blue and yellow tails against the glass for the inspection of visitors, while another walked sedately about, carrying his huge claws before him, and presenting a ludicrous resemblance to a child in its father's boots. In a neighbouring tank two spider-crabs, with heads erected, had placed themselves one on either side of an oyster in attitudes which seemed to convey scorn and defiance to each other; and a third spider-crab, who from the station he had taken up might have been desirous of seeing fair play, afforded a resting-place upon his shoulders to two hermit-crabs, who had climbed to that elevated position to obtain a better view. It is impossible to guess whether they were adequately rewarded for their trouble; for the preliminaries of the contest, or conference, or courtship, or whatever the affair might have been, were still unadjusted when it became necessary for spectators to withdraw.

In one of the tanks there is a party of hawksbillturtles, five in number, and three of these are of considerable size. The Crystal Palace Aquarium has taught us with what perfect grace and elegance the turbot, sole, plaice, and other flat fish move through the water; and the turtle is fully worthy of the same commendation. He is seen to the greatest advantage when descending, and at the same time advancing towards the spectator. If advancing directly, his head

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and flappers rather ludicrously realize the conventional cherub, and suggest that an Aquarium must have existed at a very early period in the history of sacred

art.

The oysters, apart from their important share in clearing the water, are usually unmoved spectators of the active life above them. Still, they resent liberties, and on Friday an alarm was raised by an attendant that "an oyster had collared the turtle." One of the flappers had intruded itself between the parted shells of the bivalve, and they had closed upon it with tenacious grip.

The fresh-water fish at present in the Aquarium are tench, goldfish, and chub, the latter bred and reared by Mr. Frank Buckland. That gentleman has also contributed an alligator-still a mere baby, but able to inflict a severe bite on one of the men who assisted in removing him from his travelling case.-The Times.

THE GREAT CURRENT OF THE ATLANTIC, CALLED THE GULF STREAM.

PERSONS are often prevented from inquiring into a subject, under the impression that it is too difficult for them to comprehend, when a very little attention would render it very easy.

Everybody, who has observed the stream rushing through a mill-dam into a wide basin of water, must have noticed, that a great part of the water is in constant circulation. If a chip of wood is thrown into the current, it is carried away at first very rapidly, but afterwards gets to the edge of the stream, takes a circuit, and is possibly brought back nearly to the place where it was first thrown in. This revolving motion of the

water is thus occasioned: the water next to that in the stream is dragged along with it; the removal of this causes a hollow, into which the water next to it runs;