Of the 49,423 prisoners in our city prisons, in prison for one year before January, 1870, 32,225 were of foreign birth, and, no doubt, a large proportion of the remainder of foreign parentage. Of the foreign-born, 21,887 were from Ireland; and yet at home the Irish are one of the most law-abiding and virtuous of populations--the proportion of criminals being smaller than in England or Scotland. In the Eastern Penitentiary of Pennsylvania, according to Dr. Bittinger, from one-fourth to one-third of the inmates are foreigners; in Auburn, from a third to a half; in Clinton, one-half; in Sing Sing, between one-half and six-sevenths. In the Albany Penitentiary, the aggregate number of prisoners during the last twenty years was 18,390, of whom 10,770 were foreign-born. [Transact. of Nat. Cong., p. 282.] It is another marked instance of the demoralizing influence of emigration, that so large a proportion of the female criminal class should be Irish-born, though the Irish female laboring class are well known to be at home one of the most virtuous in the world. A hopeful fact, however, begins to appear in regard to this matter; the worst effects of emigration in this country seem over. The machinery for protecting and forwarding the newly-arrived immigrants, so that they may escape the dangers and temptations of the city, has been much improved. Very few, comparatively, now remain in our sea-ports to swell the current of poverty and crime. The majority find their way at once to the country districts. The quality, too, of the immigration has improved. More well-to-do farmers and peasantry, with small savings, arrive than formerly, and the preponderance, as to nationality, is inclining to the Germans. It comparatively seldom happens now that paupers or persons absolutely without means, land in New York. As one of the great causes of crime, Emigration will undoubtedly have a much feebler influence in the future in New York than it has had in the past. WANT OF A TRADE. It is remarkable how often, in questioning the youthful convicts in our prisons as to the causes of their downfall, they will reply that "if they had had a trade, they would not have been there." They disliked drudgery, they found places in offices and shops crowded; they would have enjoyed the companionship and the inventiveness of a trade, but they could not obtain one, and therefore they were led into stealing or gambling, as a quick mode of earning a living. There is no doubt that a lad with a trade feels a peculiar independence of the world, and is much less likely to take up dishonest means of living than one depending on manual labor, or chance means of living.