All these speculations are idle, for the lights burn when the sun is shining, as well as at night; and the object of the lower one is that no trace of moisture, and no approach of cold, shall give the electricity a chance of slipping down the mast, or the ropes, to the earth, but shall leave it no way of escape from the wise men below, who want it, and will have it, whether it likes or no, in their jars, that they may measure its quantity and its quality, and write both down in their journals. It is thus that electricity comes down the wires into those jars on our right as we enter. If very slight, its presence there is indicated by tiny morsels of pendent gold-leaf; if stronger, the divergence of two straws show it; if stronger still, the third jar holds its greater force, whilst neighbouring instruments measure the length of the electric sparks, or mark the amount of the electric force. At the desk, close by, sits the observer, who jots down the successive indications. In his book he registers from day to day, throughout the year, how much electricity has been in the air, and what was its character, even to such particulars as to whether its sparks were blue, violet, or purple in colour. At times, however, he has to exercise great care, and it is not always that he even then escapes receiving severe shocks. Passing on, we approach the magnets. They are three in number; of large size, and differently suspended, to show the various ways in which such bodies are acted upon. All hang by bands of unwrought silk. If the silk were twisted, it would twist the magnets, and the accuracy of their position would be disturbed. Magnets, like telescopes, must be true in their adjustment to the hundredth part of a hair’s breadth. One magnet hangs north and south; another east and west; and a third, like a scale-beam, is balanced on knife-edges and agate planes, so beautifully, that when once adjusted and enclosed in its case, it is opened only once a year, lest one grain of dust, or one small spider, should destroy its truth; for spiders are as troublesome to the weather-student as to the astronomer. These insects like the perfect quiet that reigns about the instruments of the philosopher, and with heroic perseverance persist in spinning their fine threads amongst his machines. Indeed, spiders occasionally betray the magnetic observer into very odd behaviour. At times he may be seen bowing in the sunshine, like a Persian fire-worshipper; now stooping in this direction, now dodging in that, but always gazing through the sun’s rays up towards that luminary. He seems demented, staring at nothing. At last he lifts his hand; he snatches apparently at vacancy to pull nothing down. In truth his eye had at last caught the gleam of light reflected from an almost invisible spider line running from the electrical wire to the neighbouring planks. The spider who had ventured on the charged wire paid the penalty of such