790 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



has been tested will stand two full one-minute immersions. Wire 

 is graded and spoken of as "one-dip," "two-dip," "three-dip," or 

 "four-dip," as the case may be. As a result of the activity of the 

 representative of this OfFice, it is now possible to buy from the leading 

 manufacturers "three-dip" wire, which will undoubtedly last very 

 much longer than the ordinary "one-dip." From the facts, as far 

 as there has been time to gather them, it would appear to be some- 

 where near the truth to state that "two-dip" wire will last, under 

 ordinary conditions, twice as long as " one-dip," " three-dip " three times 

 as long, etc. "Four-dip " is mainly used for telephone and telegraph 

 lines, and it has not yet been found practicable to make it into farm 

 fences, owing to the fact that such heavy zinc coatings are apt to crack 

 and break off in structures where sharp bends of the wire are neces- 

 sary. An article describing the present state of affairs with ragard 

 to wire fencing appeared in the Yearbook of tlie Department of 

 Agriculture for 1909. It is, of course, true that a slightly higher price 

 is asked for the very highly protected wire, but as the price does not 

 rise in proportion with the probable increased length of the Hfe of the 

 wire, its purchase will be economical for those who desire to build 

 well for the future. 



The investigations have also been extended to the protection of 

 various structures of iron and steel by the use of paints, and it is 

 not an exaggeration to state that the entire science of protective 

 paints has been put on a firmer foundation, owing to the investiga- 

 tions carried on in the Ofhce of Public Roads. For the first time 

 it is possible to design and specify a protective paint which will not 

 only cover the metal, but will act as a deterrent to rusting, in case 

 water and the atmosphere penetrate to the surface of the underlying 

 steel. It has been shown that the hfe of wire fencing can be pro- 

 longed, and it has been estimated that the ordinary farm fences 

 can be painted at an expense of about 1 cent per rod. If properly 

 selected and designed, there is no doubt that the farmers can protect 

 their wire fencing for many years at a comparatively small expense 

 and with little trouble, since the painting can be done at those seasons 

 of the year when the farmer is not especially occupied with plowing, 

 planting, or harvesting. 



OIL-CEMENT CONCRETE. 



Perhaps the most important development that has attended the 

 investigative work of the Ofhce during the past year has been the 

 development of oil-cement concrete. It is very well known that 

 Portland cement concrete is rapidly becoming a universal building 

 material. It is not only used in road building, but in all forms 

 of engineering construction as well as in the construction of buildings 

 of all sorts. Its use on the farm has been very much extended, and it 

 is probable that in the not very distant future reinforced concrete 

 will be used in the construction of farm buildings, including dwelhngs. 

 The principal objection to the present use of cement concrete 

 as a material of construction hes in the fact that it is extremely 

 porous and absorbs water. On this account, it is well known that 

 buildings constructed of concrete are damp. There are on the 

 market a number of patented and secret water-proofing materials, but 

 none of these, we beheve, has given satisfactory results under the 

 varied conditions of service. 



