The laying down of an under-sea telegraph wire across the Irish Channel, may be taken as a new instance of the indifference consequent on familiarity. When the line was laid from Dover to Calais, the whole land rang with the fact; but now the sinking of a wire three times the length, in a channel three times the width, excites scarcely a remark, and seems to be looked on as a matter of course. The wire, which is eighty miles in length, is said to weigh eighty tons. It was payed out and sunk from the deck of the _Britannia_, at the rate of from three to five miles an hour, and was successfully laid, from Holyhead to Howth, in from twelve to fifteen hours; and now a message may be flashed from Trieste to Galway in a period brief enough to satisfy the most impatient. The means of travel to the East, too, are becoming tangible in the Egyptian railway, of which some thirty miles are in a state of forwardness, besides which a hotel is to be built at Thebes; so that travellers, no longer compelled to bivouac in the desert, will find a teeming larder and well-aired beds in the land of the Sphinxes. And, better still, among a host of beneficial reforms to take place in our Customs' administration, there is one which provides that the baggage of travellers arriving in the port of London shall be examined as they come up the river, instead of being sent to the Custom-house. By a report of the Astronomer-royal to the Board of Visitors, who have lately made their annual inspection of the Greenwich Observatory, we are informed, of a singular fact, that observations of the pole-star shew that its position varies some three or four seconds on repeating the observations at intervals of a few months, and this notwithstanding the extreme accuracy of the transit circle. The only explanation which can as yet be given for this phenomenon is, that the earth, solid as it appears, is liable to slight occasional movements or oscillations. We shall know, in a few weeks, the result of the telegraphic correspondence with the Observatory at Paris--one interesting point being, as to whether the respective longitudes, as at present determined, will be verified by the galvanic test. Besides which, Greenwich time is to be sent every day to London, where a pole, with a huge sliding-ball, has been fixed on the top of the Telegraph Office, near Charing Cross. This ball is to be made to descend at one o'clock simultaneously with the well-known ball which surmounts the Observatory; and thus scientific inquirers--to say nothing of the crowds who will daily throng the footways of the Strand to witness the downcome--will be informed of the true time, while, by means of the wires, it may be flashed to all parts of the kingdom.