area of Massachusetts and the population of Maryland of 1860 to the square mile, would have had then a population of only 481,728 upon that basis, leaving Massachusetts in 1860, 1,273,393 more people than Maryland. Thus is the assertion in a former part of this article now proved, 'that in the absence of slavery, the population of Maryland in 1860 would have then been at least 1,755,661, and Baltimore at least 542,000.' But, in view of the many other natural advantages of Maryland, as shown in this article, viz.: in climate and salubrity, in shore line and navigable rivers, in fertility of soil, and hydraulic power, in a more central location for trade with the whole Union, and especially with the West, and nearer supplies of cotton, and, above all, in coal and iron, it is clear, in the absence of slavery, Maryland must have contained in 1860 a population of at least two millions. By the census of 1790, Massachusetts was the fourth in population of all the States, and Maryland the sixth; but in 1860, Massachusetts was the seventh, and Maryland the nineteenth; and if each of the thirty-four States increases in the same ratio from 1860 to 1870, as from 1850 to 1860, Maryland will be only the twenty-fifth State. These facts all conclusively attest the terrible effects of slavery on Maryland, and this is only one of the dreadful sacrifices she has made in retaining the institution. As to wealth, power, and intellectual development, the loss cannot be overstated. Nor can manufactures account for the difference, as shown by the still greater increase of the agricultural North-West. Besides, Maryland (omitting slavery) had far greater natural advantages for manufactures than Massachusetts. She had a more fertile soil, thus furnishing cheaper food to the working classes, a larger and more accessible coast, and nearly eight times the length of navigable rivers, greater hydraulic power, vast superiority in mines of coal and iron, a far more salubrious climate, cotton, the great staple of modern industry, much nearer to Maryland, her location far more central for trade with the whole Union, and Baltimore, her chief city, nearer than Boston to the great West, viz,: to the Ohio at Pittsburg and Cincinnati, the Mississippi at St. Louis, and the lakes at Cleveland, Toledo, and Chicago, by several hundred miles. Indeed, but for slavery, Maryland must have been a far greater manufacturing as well as commercial State than Massachusetts--and as to agriculture, there could be no comparison.