4.8 A STATISTICAL ACCOUNT OF THE 



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

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

 that timbei-, 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 under cover. That practice has also been introduc- 

 ed into Sv/eden ; 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, wi- 

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

 supported mostly by brick v/alls on each side, to defend the 

 v/orkmen in v/inter, 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 coter the ships com- 

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

 fectly sound (in 1792) for fifty nineyears^ 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 wooden bridges in America, particidarly. It is 

 to be regretted that all these structures are thus destitute of 

 the means of preservation. I now 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 

 words:" — " To some questions you put to me some time since, 

 relative to the durability of timber bridges^ tvithout being co- 

 vered^ sides and top, I answer, from the experience tliat I 

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

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

 riages to pass over. The bridge near Newburj'port, over the 

 Merrimack, v/as built in the year 1792. It was repaired in 



