By the courtesy of Allen L. Bours, Esq., Secretary of the Board of State Building Cominissioners aud of the Committee on ' the Laying of the Corner stone, our reporter was permitted to oopy the BCCompanying concise description of the' architecture of the new Capítol froin tho account that was enrolled on parchment for deposit in thecorner-stone. Tho description was pveTjared by Mr. Bours himsulf, and is a part of the coutents of the parchment volume, containing a brief history of the State, prepared by him also. This volume, together with tho other articles, of which a list is given elsewhere, are hermetically sealed in the stone, under a slab of slate, carved with the State arms. The description is as follows : In response to an advertisemont of the (State Building) Commissioners, soliciting competitivo designs for a now Capítol, '-(I sets of drawiugs werereceivedfrom arehitects of various localities on December 28, 1871. After a careful examination of each, the board on the 21th of January, 187'2, adoptnd the design of Elijah E. Myers, Esq., an architect then residing at Springiield, Ill„ and entered ínto a contract with him as architect and general superintendent of the work until its completion. Mr. Myers immediately removed his residence to the city of Detroit, and engaged in the preparation of specitications and detail dmwings. On the lóth of July the board entered into a contract with Messrs. Neheniiah Osborn & Co., builders, of Rochester, N. Y., and Detroit, for the construction of the entire building. At an extra session of the Legislature, in March, 187'J, the cost of tho building, with all expenses incident to its erection, was limited to $1,200,000. The sum agreed upon in the contract is f1,144,057.20, leaving nearly $56,000 to cover extras, salaries,and other expenses. The building will be of the Palladian style of architecture, which was adopted by the architect as best suited to the appea ranee of grandeur, required in a building of this cïass. The outline is sufficiently broken to produce pleasing contrasts of light and shade ; while the architect has studiously observed the suggestion of the coinmissioners in avoiding supertluous ornainentation, preserving solidity and compactness, and at the same time giving to each apartment an abundance of light. The arrangement of the various offices and departments will be exceedingly convenient; special attention havingbeen given in this respect to the wants of the public as well as to the offices having business with each other. The foundation walls to the earth line are of Lamont, Illinois, liinestone, in massive blocks extending the entire width of the wall and underlined with concrete to the depth of throe feet. The superstructure is to be of sandstone froni Amherst, Ohio, and the partition walls and backings to exterior walls will be of hard burned bricks. The girders, beams, joists, roof and dome will be made exclusively of iron, of which material all partitions will be made, except where constructed of masonry. The stairs throughout the building, including steps, risers, hand-rails, balusters, and bearers, will be exclusively of iron. The corridors, from the basement to the top of the building, will be paved with marble and slate. The most approved arrangements will be employedfor ventilation, steam-heating, and lighting by gas. The basement story will contain an armory connected with the department of the Quartermaster General, and the remainder of the story will be devoted at present to storage, although, the rooms being high and well-lighted, and ventilated, will make excellent offices, should they be required at any timeforthat purpose. The first story, which will be 20 feet in height, will contain offices and private apartinents for the various State offices and bureaus. Upon this floor will be a main corridor extending acrosa the building froin east to west, through the rotunda, under the dome, and crossed at right angles by a corridor JÏ45 feet in length, extending from the north to the BOuth entrance. The rotunda will be paved with hexagon blocks of glass, six inches in diameter and an inch and a half in thickness, supported by a frame of iron into which each piece will be closely fitted. From this rotunda, which is 44 feet in diameter, the interior of the dome, open to the height of 175 feet, inay be seen, with galleries extending in it froin each of the stories above. Upon the second floor, at the north end of tho building, will be the Hall of llepresentatives, occupying the height of two stories, 40 feet. This hall will be 70 feet in width by 77} in length, with galleries upon the east, south, and west sides. The south gallery will extond back 22 1-2 feet, making the upper portion of the rooia 100 feet in length. There will be no columns or other like obstructions in this hall, the ceiling of which is to be of embossed colored plate glass, will be supported by the iron roof trusses, and the galleries will be supported by iron girders entirely hidden from view. The hall will be lighted by nine windowa on each side, four on the lower floor and five on the upper, and by a large sky-light in the roof over the glass ceiling. The gaslight will be reñeeted down through this ceiling. The Sonate Chamber at the south end of the building will correspond, in all respects but sizo, with the Representative Hall, it being of the same width, but shorter by 12 feet. Between the Legislative Halls, at the west front of central portion of the building, will be the hall for the State Library. This hall will be 100 feet in length, 40 feet wide, and open to tho top of the building, a height of 50 feet, withgalleï ies containing alcoves for the convenient arrangement of books. At the east front, upon the same floor, will be a suit of rooms for the Governor and his Secretary. Over the Governor's rooms, upon the third floor, will bo the Supreme Court room, with rooms in close proximity, for the accommodation of the judges andattorneys, and offices of the Attorney General. The remainder of the necond and third stories will be devoted to committee rooms and other apartments required for the Legislature. On either sido of the rotunda a grand stairway rises from the basement to the fourth story, private stairways being provided in other portions of the building as convenience may require. An elevator, to be operated by steain, will be situated in the central portion of the building. The roof will be of corrugated galvanized iron, constructnd in such a munner that no trouble will be occasioned by the lodgment of snow or ice and the necessity for repairs cannot occur with frequency. All the windows will be glazed with polished English or Berlin plate glass, - one plate to aach sash. Tho inain pediment of the building looking east, will contain an allegorical represeutation of the rise and progress of Michigan, carved in bas relief. The stipulated date for the completion of the building is the first day of December, 1S77. The principal dimensions of the building are as follows : Length, not including pórtico, 345 feet 2 inchss; depth, 19] feet 5 inches; height of lantern, 265 feet. THE FOUNDATION, The Capítol grounds have been a natural objoot of curiosity to the traveling stranger tor months past. But the excavations and sheds for stone-cutting and carpentery have been for a long time surrounded by a high fence, and during the summer the gates have always been olosed at 6 o'olock at night. Ten strong derricks are scattered throughout the acre or two of cellar, and the tall, straight oaken mast make the distant gazer think of ship-yaids and harbors. In passing through the streets he sees Btout, slow moving wagons drawn, sometimes by doublé teams, and bearing each a huge block of lime-stone nearly a foot thiok and eight or ten feet long, by tour orlive wida. When these pass through the gate they pasa between. a raountain of btick f and a desert of sand, and stop near one of the large derricks. The beam swings slowly round, a workman with a few strokes of a mallet ind ohisel chipa away a cavity in either side of the stone, great ron olamps clasp it, and thon lifting it over 11 few rods of spaoe lays it lightly as i pillow ia ta plaoe in tho foundation. Theso powerful angines are üisily 111,111agcd, all being controlled by a l'ing, slender shaft connected with the stuam eiigine at one end, and so eonnocted with the derricks that a boy, by moving a lever, oan set in motion massus of liine-stoiiB weigliing thousands of pounds. It has been the design to complete the foundation as nearly as possible before the laying of the corner stone. The wall rests on a solid mass of concrete that constantly hardens uutil it is like rook itself. This concrete subbtraturu extends about three feet into the earth, but in some places, whore the diggers struck a sand layer, it goes to the depth of ftom l(i to IS feet, the purpose being to have an immovable basis. Iu the centre of the cellar excavation is a circle of concreto rive feet deep and 1 ■" broad, to support the treiuendous dome. The concrete hardens so that one or two pieces which havo been taken out show that it is in the most satisfactory condition. The surface of one piece that had been in for a couple of months was hard enough to be giound, and when ground had tb e likeness of a conglomérate or pudding-slone. For months a powerful littlo machine m the yard was kept snapping its ugly iron jaws on pieces of stone, which crunched into smaller fragnients for use in the composition of this hardeuing substance. Fc under gronnd, belovv the foundation, is an interlacing system of draimng pipes, that is expected to provide the most perfect sewerage for the wholo building.