The imprisonment, of males, for offenses which boys are likely to commit, though not so encouraging as with the girls, shows that juvenile crime is fairly under control in this city. Thus, "Vagrancy" must include many of the crimes of boys; under this head we find the following commitments of males:-- 1859..........2,829 1860..........2,708 1862..........1,203 1864..........1,147 1865..........1,350 1870..........1,140 1871............984 In twelve years a reduction from 2,829 to 994, when the natural increase should have been up to 3,225. Petty larceny is a boy's crime; the record stands thus for males:-- 1857..........2,450 1859..........2,626 1860..........2,575 1865..........2,347 1869..........2,338 1870..........2,168 1871..........1,978 A decrease in fourteen years of 502, when the natural increase should have brought the number to 2,861. Of boys under fifteen imprisoned, the record stands thus since the new classification:-- 1864..........1,965 1865..........1,934 1869..........1,873 1870..........1,625 1871..........1,017 Of males between fifteen and twenty, in our city prisons, the following is the record:-- 1857..........2,592 1859..........2,636 1860..........2,207 1861..........2,408 1868..........2,927 1870..........2,876 1871..........2,936 It often happens that youthful criminals are arrested who are not imprisoned. The reports of the Board of Police will give us other indications that, even here, juvenile crime has at length been diminished in its sources. ARRESTS. The arrests of pickpockets run thus since 1861, the limit of returns accessible:-- 1861............466 1862............300 1865............275 1867............345 1868............348 1869............303 1870............274 1871............313 In ten years a reduction of 153 in the arrests of pickpockets. In petty larceny the returns stand thus in brief:-- 1862..........4,107 1865..........5,240 1867..........5,269 1870..........4,909 1871..........3,912 A decrease in nine years of 195. Arrests of girls alone, under twenty:-- 1863..........3,132 1867..........2,588 1870..........1,993 1871..........1,820 It must be plain from this, that crime among young girls is decidedly checked, and among boys is prevented from increasing with population. If our readers will refer back to these dry but cheering tables of statistics, they will see what a vast sum of human misery saved is a reduction, in the imprisonment of female vagrants, of more than five thousand in 1871, as compared with 1869. How much homelessness and desperation spared! how much crime and wretchedness diminished are expressed in those simple figures! And, if we may reckon an average of punishment of two months' detention to each of those girls and women, we have one hundred and twenty-five thousand dollars saved in one year to the public by preventive agencies in this class of offenders alone.