Page 158.--"In the neighborhood of London the materials that are to be procured are of too tender and brittle a nature to endure the wear of the heavy carriages. I, therefore, am of the opinion that it would be proper to pave the sides of all the principal entrances into London." Page 166.--"James Walker says, 'The traffic upon the Commercial rail road, both up and down, is very great. I am quite sure that the expense of this road would have been very much greater, probably much more than doubled, if it had not been paved. The road has been paved for about sixteen years, and the expense of supporting it has been small. During the thirteen years that the East India dock branch has been paved, the paving has not cost £20.'" Page 167.--"But as the paving is always preferred for heavy carriages," &c. Page 172.--"The thickness ought to be such, that the greatest weight will not effect more than the surface of the shell, in order to spread the weight which comes upon a small part only of the road over a large portion of the foundation." Page 173.--"If the foundation is bad, breaking the bottom stone into small pieces is expensive and injurious, upon the principle I have above described, for the same reason that an arch formed of whole bricks, or deep stones, is preferred to one of the same materials broken into smaller pieces, for, in some countries, the materials will admit of the foundation of the road being considered as of the nature of a flat arch, as well as being supported by the strata directly under it. But the error of laying stones in large pieces upon the surface is more common and more injurious." Page 183.--"James Dean says, 'Near to great towns it would be highly advantageous if the center of the road, for about twelve feet in width, were to be paved with hard, well-squared stones, nine inches deep.'" Page 188.--"Thomas Telford, Esq., says, 'The improvements made in North Wales I beg leave to submit as models for the roads through hilly countries. Great pains have been taken in constructing firm and substantial foundations for the metallic part of the roadway.'" Page 189.--"There has been no attention paid to constructing a good and solid foundation for the roadway." Page 192.--"Are you of the opinion that it would be advisable or practicable to procure, from any particular part of the country, better materials, so as to form perfect roads without the necessity of paving them? That these materials could be procured, is evident; but I am satisfied that the most economical and preferable mode would be by the means of paving." * * * * * ENGINEER DEPARTMENT. WASHINGTON. May 8, 1833.