I begin with Maryland, because, in proportion to her area, she has greater natural advantages than any one of the thirty-four States, and, if the comparison with the free States is most unfavorable to her, it will be more so as to any other Southern State, as the census shows that, from 1790 to 1860, and from 1850 to 1860, Maryland increased in population per square mile more rapidly than any other slaveholding State. Maryland borders for two hundred miles the great free State of Pennsylvania, and Delaware one hundred and thirty miles, whose slaves have decreased from 8,887 in 1790, to 1,798 in 1860, and where slavery now exists in name only. Delaware, like Maryland, is also a loyal State, and would be the last to leave the Union, which it was her glory first to enter under the Constitution of 1787. On the west, Maryland is bounded by Preston county, Virginia, containing in 1860 a free population of 13,312, and 67 slaves only. Western Virginia, bordering Maryland on the south, has voted with great unanimity to become a free State, and all appearances indicate that slavery will disappear from Virginia with the close of this year. Maryland then would be surrounded entirely by non-slaveholding States. Within the heart of Maryland stands this District, where slavery is now abolished, producing serious losses and embarrassments to the State. The two counties of Prince George and Montgomery, adjoining this District, contained in 1860, 17,790 slaves, being more than one fifth of the slaves of the State. How long can slavery endure, and of what value is it in these counties, where every slave brought or sent to the District is free, and where it is already seriously contended that the language of the Constitution, 'slaves in one _State_, escaping into _another_,' cannot apply to this District? With the feeling so intensified already by this rebellion against slavery, it cannot long exist in Maryland. By advancing legislation, and public sentiment, the fugitive slave law is becoming inoperative, and slaves in Maryland are now held by a most precarious tenure. Indeed, unforeseen events, as this terrible rebellion progresses, may sweep slavery from Maryland without compensation or colonization. But, independent of present or future perils, it is proposed to prove, mainly by the census, that all the material interests of Maryland would be greatly promoted by her prompt acceptance of the offer of Congress. We must consider the area, soil, climate, mines, hydraulic power, location, shore line, bays, sounds, and rivers, and such other causes as affect the advance of wealth and population.