The following account of the laying of the corner-stone of the extensions, July 4, 1851, is taken from the National Intelligencer of the 7th :

The National anniversary was, in its important incidents, the fineness of the weather, and its freedom from all untoward occurrences, perhaps the most interesting and agreeable ever enjoyed in this capital.

The day was ushered in by salutes of artillery from different points of the city, and, as the glorious sun gilded our tallest spires, and shed a lustre on the dome of the Capitol, it was welcomed by a display of National Flags and the ringing of bells from the various churches and engine houses. Thousands of visitors from Georgetown, Alexandria, Prince George's, Montgomery, Virginia, and Baltimore poured in by every kind of conveyance. A very large proportion of these hastened to the Capitol, in hopes to secure an eligible place from which to hear Mr. Webster's speech ; others again pressed their way to the City Hall, to witness the first moving of the procession.

In the large Council Chamber of the City Hall were assembled the President of the United States, the Members of the Cabinet, Officers of the Army and Navy in full uniform, the Mayor and Members of the Corporation, and various civil officers.

At the appointed hour the various bodies were drawn into line. The first division of the procession was for the most part of visiting and local military companies. The array of officers of the Army and Navy was one of the most imposing features of the pageant, including amongst them 30 or 40 brave veterans with the Commander-in-Chief Scott at the head of the Military Division, and Commodore Morris at the head of the Naval, all in full uniform ; Officers of the several States and Territories ; officers and soldiers of the Revolution ; and officers and soldiers of the War of 1812.

Then came the Civic Procession, composing the second, third, fourth, and fifth divisions of the program :

The second division was under Dr. William B. Magruder, as Marshal, and was arranged in the following order :

Persons present at the laying of the corner-stone of the Capitol in 1793. The President of the United States and Mayor of the City. , Heads of Departments.

Cabinet Members of former Administrations. Committees of Public Buildings of the Senate and House of Representatives, Architect of Capitol, Commissioner of Public Buildings. Heads of Bureaus. Judges of the United States Courts. Judges of the State Courts. Chaplains of the 31st Congress.

The Reverend Clergy of the District. Delegations from States and Territories.

Washington Monument Society. Members of the Smithsonian Institution.

Members of National Institute. Ex-Mayors of the City of Washington. The Corporate authorities of Alexandria, Georgetown and Washington. Members of the Society of Cincinnati.

The third division consisted of the Fraternity of Free and Accepted Masons, who were attired in the regalia of the Order, bearing its various emblems, and forming a distinct feature in the pageant. Then followed the order of the Sons of Temperance, including their grand and subordinate divisions, with banners, etc., as before described.

In about 30 minutes, the Procession entered the North gate of the Capitol grounds, and were drawn up in order around the excavation for the Cornerstone. The President of the United States, attended by Walter Lenox, Esq., Mayor of the City of Washington; the Heads of Departments ; the Officers of the Army and Navy ; George Washington Parke Custis, Esq.; the Reverend Clergy; the Masonic Order; and as many others as the limited space would accommodate, occupied the site of the contemplated edifice.

After a salutatory by the Marine Band, and order being proclaimed, the Rev. C. M. Butler, D.D., Rector of Trinity Church, and Chaplain of .the Senate, opened the ceremonies with fervent and impressive prayer.

Thomas U. Walter, architect of the new building, then took a survey of the stone and deposited therein a glass jar, hermetically sealed, which contained a variety of valuable historical parchments, the coins of the United States, a copy of the Oration to be delivered by the Secretary of State, newspapers of the day, and other memorials.

The Corner-stone of the new Capitol edifice was then, with great dignity and solemnity laid by Millard Fillmore, President of the United States, after which he gave way to the Masonic Fraternity.* Then services were opened with an excellent prayer by the Grand Chaplain, the Rev. Charles A. Davis. The "corn of nourishment, the wine of refreshment, and the oil of joy," were severally deposited according to the peculiar observances of the fraternity, viz.:

The Grand Master examined the stone, applied the Square, level and plumb, and pronounced it properly formed, and of the suitable material for the purpose for which it was intended. He. then placed upon it the corn, wine, and oil, saying as he did so, " May the all bountiful Creator bless the people of this nation, grant to them all the necessaries, conveniences, and comforts of life ; assist in the erection and completion of this edifice, preserve the workmen from any accident, and bestow upon us all the corn of nourishment, the wine of refreshment, and the oil of joy." He then said, "with this gavel, which was used by the immortal Washington, at the laying of the corner-stone of that Capitol, and clothed with the same apron that he then wore, I now pronounce this corner-stone of this extension of that Capitol, well laid, true, and trusty," accompanying the last words with three blows of the gavel. He then presented to T. U. Walter, Esq., the Architect, the working tools, being the square, level, and plumb, accompanying the presentation with the following remarks :

" Mr. Architect: I now, with pleasure, present to you these working tools of your own profession—the square, the level, and the plumb. We, as speculative masons, use them symbolically ; you as an accomplished architect, well know their use practically, and may the noble edifice, here to be erected, under your charge, arise in its beautiful proportions, to completion, in conformity with all your wishes, and may your life and health be long continued, and may you see the work go on, and the cap-stone laid under circumstances as auspicious and as happy as those under which the corner-stone, is this day laid".

* Matthew G. Emory, ex-Mayor of the City of Washington, who built the basement stories of the extensions, furnished all the granite and delivered the white marble for the wings, laid the corner-stone in preparation for the ceremony.

The line of the procession and the mighty multitude now changed positions nearer to the front of the stand from whence the addresses were to be delivered. Accompanied by the marshals of the day, the President and his escort, with the distinguished individuals already referred to, were conducted to seats upon the lofty platform.

15. B. French, Esq., Grand Master of the Masons, then appeared in front (preceding Mr. Webster at his request), and delivered the opening address.

Mr. Webster then rose from a chair next to President Fillmore and approached the front of the stand. He was welcomed by the hearty cheers of the multitude, and proceeded to read the address which he had prepared, a copy of which had been deposited in the corner-stone. He did not, however, confine himself to the manuscript, but occasionally extemporised new thoughts and other highly interesting reflections which together with the reading, occupied nearly two hours.

The conclusion of these important ceremonies was announced by a salute of artillery from the public reservation at the north end of the Capitol and the military and civic associations returned in excellent order to their respective places of rendezvous where they were dismissed.

The glorious day closed with a display of fire-works from the Mall south of the President's house.

Webster's oration was one of the most eloquent and comprehensive in his career. It was listened to by a large assemblage of people, who filled the eastern plaza before the Capitol, a much smaller amphitheater, however, than that to the east of the building at the present time. In the course of his address he called attention to the following account of the proceedings of the day, which, in-his own handwriting, had been deposited within the corner-stone :

" On the morning of the first day of the seventy-sixth year of the independence of the United States of America, in the city of Washington, being the fourth day of July, 1851, this stone, designated as the corner-stone of the extension of the Capitol, according to a plan approved by the President, in pursuance of an act of Congress, was laid by Millard Fillmore, President of the United States, assisted by the Grand Master of the Masonic Lodges, in the presence of many members of Congress ; of officers of the executive and judiciary departments, national, state and district; of the officers of the Army and Navy ; the corporate authorities of this and neighboring cities ; many associations, civil, military and masonic ; officers of the Smithsonian Institution, and National Institute ; professors of colleges and teachers of schools of the District of Columbia with their students and pupils ; and a vast concourse of people from places near and remote, including a few surviving gentlemen who witnessed the laying of the corner-stone of the Capitol by President Washington, on the 18th day of September, 1793.

" If, therefore, it shall hereafter be the will of God that this structure shall fall from its base, that its foundations be up-turned, and this deposit brought to the eyes of men, be it known that, on this day, the Union of the United States of America stands firm ; that their constitution still exists unimpaired, and with all its original usefulness and glory, growing every day stronger and stronger in the affections of the great body of the American people, and attracting more and more the admiration of the world.

"And all here assembled, whether belonging to public or private life, with hearts devoutly thankful to Almighty God, for the' preservation of the liberty and happiness of the country, unite in sincere and fervent prayers that this deposit and the walls and arches, the domes and towers, the columns and entablatures, now to be erected over it, may endure forever ! God save the United States of America !

Daniel Webster, Secretary of State of the United Slates".