By the latest news from Europe, we learn that very active preparations are now making for the next effort in laying the Atlantic telegraph cable. Our noble frigate, the Niagara, with the British war steamer Agamemnon, her former companion, are taking in their shares of the cable, and they will be in readiness to proceed on the expedition about the end of May. Great care has been taken in the construction of the paying-out machinery, and after it is all completed, the most intelligent machinists in England are to be invited to inspect it and offer critical observations. When no good cause can be shown for further alterations in the machinery, both vessels will proceed to sea, and rehearse a series of experiments in paying out and hauling in the cable, then return to England and report the results. Should these be satisfactory, the final expedition will sail soon afterwards. Instead of commencing to lay down the cable on the Irish coast, as formerly, they will sail out to mid-ocean, divide, and commence paying out from the two vessels at once—stern to stern—the one steaming for England, and the other for Newfoundland. The principal directors in the last expedition are to occupy the same positions in the next. Mr. Bright is still chief engineer, and from his former experience it is reasonable to , suppose he will neglect no precaution to ensure success. A great number of patents rthave recently teen taken out in England for machines to pay out the cable. The directors of the Telegraph Company have quite a variety of such to select from, and we hope they will choose the best. They seem to have confidence in the entire success of this second attempt, as they have employed a staff of operative telegraphers to practice on the coils to perfect themselves, and be in readiness for immediate action as soon as the cable is laid. If any impediment should stand in the way of success in this fresh attempt, it will not be caused by a want of attention to the several partsof the work, for each will have to pass through a most rigid ordeal of experiment, under the immediate inspection of the most distinguished scientific men of the world. From recent experiments on the coils, as stated in English papers, it would appear that only about eight words per minute can be sent through the cable—very slow work indeed—but such as seems to accord with the deductions published on page 184 of the last volume of the SCIENTIFIC AMERICAN. About fifty-two miles of the lost cable— some of which lay one thousand fathoms deep —have been fished up. It was in as perfect a state as when first laid down, as regards its electrical conditions, but showed signs of the outer covering of the spiral wires having stretched considerably.