L. MECHANICS AND ENGINEERING. 471 



Dubois' peintuke hydkaulique. 



At the recent French Maritime Exhibition, one of the most 

 interesting exhibits consisted of several large iron plates, in- 

 closed by cords and sealed by the Department of the Fonts 

 et Chaussees as having remained under water, submerged in 

 the sea, for a period of eight consecutive months. These 

 plates are exhibited by M. Dubois, in order to show the qual- 

 ities and merits oi his peiiiture hydraulique hydraulic paint 

 or anti-fouling composition, and, if accounts may be cred- 

 ited, they bear conclusive testimony to the excellent qualities 

 of the composition. In one case, we learn, about half of the 

 plate was left untreated, the other being duly coated with M. 

 Dubois' preparation ; with the two others, one half was coated 

 as above with the hydraulic paint, Avhile the other half was 

 treated with the compositions of a similar kind most in vogue 

 in France. In all three cases, our informant proceeds, the 

 half of the plate treated with the Dubois preparation was 

 found to be perfectly free from rust, as well as from all out- 

 growth or incrustation of weeds and shells ; remaining, in 

 fact, as clean and bare as on the day when it was immersed. 

 The advantages claimed, and thus demonstrably established, 

 for this anti-fouling composition are its cheapness, solidity, 

 and durability, and the extremely valuable quality of prevent- 

 ing oxidation and the adherence of mollusks and sea-weed. 

 These qualities, it would seem, should make the preparation 

 admirably adapted as a protecting coating for iron and cop- 

 per-sheathed ships. Iron Age^ VI., 451. 



/THE AQUOMETEE. 



A new steam-pump with tlie foregoing name was on exhi- 

 bition at a late fair of the American Institute. In external 

 appearance, as well as in construction, it bears a strong re- 

 semblance to the apparatus known as the Pulsometer, which 

 is doubtless well known to our mechanical readers. The fol- 

 lowing description of the Aquometer will explain the princi- 

 ples of construction and action. There are two working 

 chambers combined with an interposed pressure chamber. 

 According to the position of a steam-valve, the steam enters 

 one chamber or the other, and presses on the surface of 

 the water in the chamber, forcing the same out. As soon as 



