62 ANNUAL OF SCIENTIFIC DISCOVERY. 



another spiral cone, having at the extremity of its axle a second wheel 

 and pinion similar to the first. As the float moves with the tide, the 

 wheels and pinions connected with the cones, over which the cords of 

 the float and balance-weight respectively pass, move the rollers on 

 which the gauze web travels. On this web are painted in large fig- 

 ures the various depths, from high to low water ; and, as the web 

 works, two points on it indicate the number of feet and half-feet on 

 the bar at any hoar of the tide. At night the figures are lighted up. 

 The apparatus occupies so little space that it can all be contained and 

 worked in a column or pillar without any other building. Civil 

 Engineer and Architect's Journal, March. 



IMPROVED FILTERS. 



DR. E. WATERS, of Troy, N. Y., has invented and patented a new 

 and improved filter for the use of druggists and chemists, which is 

 designed principally to prevent the leakage and rupture so common 

 when a large filter is filled with a heavy substance. The filter is 

 manufactured of cotton and woollen, so combined as to render it ex- 

 tremely porous, and at the same time capable of filtering clearly. The 

 usual difficulty of filters wearing away at their points has been ob- 

 viated by inserting, during the process of manufacture, at the extreme 

 end of the cone, a small piece of paper composed of entirely different 

 materials, so strong in texture as not to give way by any ordinary 

 chafing or pressure. This article supplies a desideratum long felt, 

 and we understand that a paper-mill in Troy is now exclusively en- 

 gaged in the manufacture of these filters. Editors. 



IMPROVEMENTS IN DISTILLING SALT WATER, AND IN VENTILATING 



VESSELS. 



JAMES MURDOCH has secured a patent in England for improvements 

 in converting sea-water into fresh, and for ventilating ships. The 

 patent is also applicable to the evaporation of liquids, and to the con- 

 centration and crystallization of sirups and saline solutions. These 

 improvements consist in the adaptation to the top of an ordinary ship's 

 boiler, which is filled with salt water, of a pipe, which descends into 

 the hold and opens into a vessel contained in an outer casing filled 

 with cold water. This vessel is fitted with a number of vertical tubes 

 in communication with the descending pipe, and all provided inside 

 with a number of horizontal disks of wire-gauze. It terminates at the 

 bottom in a zigzag pipe, which passes through the side of the cold- 

 water cistern and opens at the top underneath an exhausting pan. 

 The upper part of the boiler is furnished with a perforated tube, which 

 admits atmospheric air. When the fan is set in motion, the air and 

 steam generated in the boiler are drawn together down the vertical 

 pipe, through the tubes and the wire-gauze disks placed therein. The 

 steam is condensed in its passage and rendered pleasant to the taste 

 by mingling intimately with the atmospheric air, which is exhausted 

 by the fan, and thereby discharged. The ship may be ventilated by 



