MEMOIR OF DANIEL TKEADWELL. 347 



These presses were sold for about ^1,000 each. Few printers thought it 

 advisable to invest in a single press an amount of money ordinarily sufficient to 

 establish a complete office. Indeed, it was only in large concerns that the work 

 required it. By the sale of these presses, with the rights to use them in several of 

 the large cities, and the building of steam-engines to drive them, Mr. Treadwell 

 added to his property about $70,000. 



I 



While engaged in printing, Mr. Treadwell made Avith the hydrostatic press used 



in his establishment a series of experiments on the effects of fluids under pres.sure 

 on different kinds of wood placed in the cylinder of the press. A piece of dry birch 

 weighing 47 grains was subjected to a pressure on all sides equal to 2,000 pounds 

 on each inch of its superficies. It was found after one minute to have gained 

 40 grains, and its specific gravity to exceed considerably that of water. This pressure 

 is about equal to that of the ocean at the depth of 4,500 feet. 



" 111 another experiment the following substances were placed in the cylinder together : a 

 mackerel weighing 4,416 gr. ; a piece of tlie tooth of a hippopotamus, 4G0 gr. ; a lemon, 1,320 

 gr. ; an egg, 798 gr. ; three pieces of cork, 147 gr. The pressure applied was about 4,000 

 pounds per inch, equal to the pressure of a column of water about 9,000 feet high ; it was 

 continued about five minutes. The mackerel was found to have lost 40 gr. ; the piece of tooth 

 gained 3 gr. ; the lemon, 16 gr., and the corks 40 gr. The egg was broken, contrary to expec- 

 tation, as it was thought not unlikely that the water would have passed through the shell fast 

 enough to have equalized the pressure. The diminution of the weight of the mackerel, about 

 one per cent, is not satisfactorily accounted for." * 



In the hope of making these results of his experiments practically useful, the 

 following communication was made by Mr. Treadwell to the Commissioners of the 

 United States Navy. 



" Boston, June 13, 1823. 



" I take the liberty of laying before you an account of some experiments I have lately 

 made, with a view of ascertaining the practicability of injecting timber with fluids, for the 

 purpose of preserving it from decay. 



" You are so well acquainted with the importance of this object that I cannot doubt that 

 every project relating to it will receive a proper examination. 



" I shall not take up your time by any review of the various schemes heretofore proposed 

 for this purpose, as they are all well known to you. But I shall commence with the supposi- 

 tion that docking, or a thorough soaking in salt water, is the best preservative against decay 

 now known. If timber be placed green in sea-water, or a solution of salt and water, the vessels 

 filled merely with air no doubt take up a portion of the fluid ; while the sap (which is justly 

 considered as the great destroyer) becomes neutralized by taking a part of the salt into solu- 

 tion from the water which formerly contained it. These actions arc necessarily exceedingly 



* Boston Joiu-Dal of Philosophy .lud the Arts, Vol. I. p. 578. 



