can anyone tell me what the nails in the end of railroad ties,with the numbers are for?

Answer 1

A Date Nail is a nail with the date stamped in its head. For example, a nail with a "41" is from 1941. They are usually 2 1/2" long, with 1/4" shanks. Date nails were driven into railroad ties, bridge timbers, utility poles, mine props, and other wooden structures for record keeping purposes. I concentrate primarily on the nails used by railroads. For a good site on date nails from poles, go to Scott Weed's site: http://nailhunter.com.
Most date nails are steel, though many are copper, aluminum, malleable iron, or brass. Lengths run from a paltry 3/4" up to 3", with shank diameters running from 1/8" up to 5/16". The nail heads can be round, square, diamond, pentagon, as well as other rarer shapes. Over 2,000 different date nails were used by North American railroads which show the year. Add to that the nails which tell wood, treatment, and other information, and toss in all date nails used in poles and other timbers, and the total number of different nails from this continent easily exceeds 3,500.

(view picture at site)
A typical date nail. This one was manufactured to be 2 1/2" long (it was cut a little short), and is made from steel wire 1/4" in diameter. The date 18 (1918) is stamped in the head. Note the crude, somewhat faint diamond on the shank to the left of the anchor markings. It might look more like a horizontal blob on this nail. It indicates that the nail was made by American Steel & Wire Co.


Read a lot more at the site.

Answer 2

The identification is correct. The nails were dated.

The reason why, is that in a by-gone era, when maintenance was required and records were not well kept, the date nail was a way of simply determining how long a cross tie had been in the ground.

It was an inexpensive back up of information. Some are worth a good deal of money, to a collector.