1. For those of an extensive nature, such as bridges, &c. The Hollanders use for the preservation of their sluices and floodgates, drawbridges, and other huge beams of timber exposed to the sun and constant changes of the atmosphere, a certain mixture of pitch and tar, upon which they strew small pieces of shell broken finely--almost to a powder--and mixed with sea-sand, and the scales of iron, small and sifted, which incrusts and preserves it effectually. 2. A paint composed of sub-sulphate of iron (the refuse of the copperas pans), ground up with any common oil, and thinned with coal-tar oil, having a little pitch dissolved in it, is flexible, and impervious to moisture. 3. Linseed oil and tar, in equal parts, well boiled together, and used while boiling, rubbed plentifully over the work while hot, after being scorched all over by wood burnt under it, strikes half an inch or more into the wood, closes the pores, and makes it hard and durable either under or out of water. 4. For fences, and similar works, a coating of coal-tar, sanded over; or, boil together one gallon of coal-tar and 2½ lb. of white copperas, and lay it on hot. TO PREVENT ROT. 1. Thoroughly season the wood before fixing, and when fixed, have a proper ventilation all round it. 2. Charring, after seasoning, will fortify timber against infection, so will a coating of coal-tar. TO CURE INCIPIENT DRY ROT. 1. If very much infected, remove the timber, and replace with new. 2. A pure solution of corrosive sublimate in water, in the proportion of an ounce to a gallon, used hot, is considered a very effectual wash. 3. A solution of sulphate of copper, half a pound to the gallon of water, laid on hot. 4. A strong solution of sulphate of iron; this is not so good as sulphate of copper. 5. A strong solution of sulphates of iron and copper in equal parts, half a pound of the sulphates to one and a half gallon of water. 6. Paraffin oil, the commonest and cheapest naphtha and oil, or a little resinous matter dissolved and mixed with oil, will stay the wet rot. 7. Remove the parts affected, and wash with dilute sulphuric acid the remaining woodwork. 8. Dissolve one pound of sulphate of copper in one gallon of boiling water, then add 1¼ lb. of sulphuric acid in six gallons of water, and apply hot. TO PREVENT WORMS IN TIMBER. 1. Anointing with an oil produced by the immersion of sulphur in aquafortis (nitric acid) distilled to dryness, and exposed to dissolve in the air. 2. Soaking in an infusion of quassia renders the wood bitter. 3. Creosoting timber, if the smell is not objectionable. 4. Anointing the timber with oil of spike, juniper, or turpentine, is efficacious in some degree. 5. For small articles, cover freely with copal varnish in linseed oil. TO PREVENT WORMS IN MARINE BUILDING. 1. A mixture of lime, sulphur, and colocynth with pitch.