43 A STATISTICAL ACCOUNT OF THE 



liament, by the Commissioners of Land Revenue, dated Fe- 

 bruary 6th, 1792, it will be found stated, from settled facts, 

 that timber, secured in the manner here proposed, is of very 

 long duration :" 



" Ships built under cover are the most durable. In Ve- 

 nice, ships have, for a long course of time been built and pre- 

 served imder cover. That practice has also been introduc- 

 ed into Sweden ; and is mentioned by Mr. Necker, in his 

 treatise on the finances of France. The Venetian ships of war 

 are built and preserved from the weather while building, un- 

 der sheds covered with tiles, resembling the roofs of houses ; 

 supported mostly by brick walls on each side, to defend the 

 workmen in winter, from the inclemency of the weather; 

 which walls are as high as the upper parts of the ships reach, 

 and secured by cross-beams, high enough to admit of ships 

 being launched under them. The sheds cover the ships com- 

 plctelij on both sides ; but are open at the stem and stem: on- 

 ly projecting a few feet farther out ; and there they have tem- 

 porary covers of boards to keep out the rain. Eighteen large 

 ships, some pierced for 80 guns, had been thus preserved, per^ 

 fecthj sound (in 1792) for jifty nine years, under the sheds." 

 " I contrast with the foregoing facts, those I have collected 

 on the subject of timber generally ; and those relative to the 

 uncovered v/ooden bridges in America, particularly. It is 

 to be regretted that all these structures are thus destitute of 

 the means of preservation. I nov,^ confine myself to the ac- 

 count of them I recently received from Mr. Timothy Pal- 

 mer ; in a letter dated the 10th of December last, in these 

 v/ords:" — " To some questions you put to me some time since, 

 relative to the durability of timber bridges, -without being co- 

 vered, sides and top, I answer, from the experience that I 

 have had in New England and Maryland — that they will not 

 last for more than 10 or 12 years, to be safe for heavy car- 

 riages to pass over. The bridge near Newburyport, over the 

 Merrimack, was built in the year 1792. It was repaired in 



