His professional career and services began in his eighteenth year- One of his first appointments was on the Croton .\queduct, where he served some years. He was subseiiuently em[)loyed upon the Erie Railway, and after that upon a road in Canada. Thence he went to t/uba in 1842, remaining there nearly a year on the Coliseo Railroad. Upon his return to this country, in 1843, and for ten yeare after, he was engaged in the Cumberland coal region . of Maryland, which he was principally instrumental in developing. While there he constructed an inclined plane, opened and worked

the mines, and made many experiments in machinery and in the combustion of coal that have been of value to the profession.

In the year 1857 Colonel Davidson went to Havana, Cuba, under an ap[)ointment as engineer-in-chief of the Havana Railways, an office he filled with great credit to himself and advantage to the company, until he resigned his position in the year 18fi8.

During the |)eriod Colonel Davidson was in Cuba he reconstructed the entire length of the nearly wornout road, some one hundred and ten miles long, elevating it from a condition of almost complete uselessness to a first-class railway in all respects. The improvements introduced by him covered everything relating to permanent way, bridges, passenger, freight and water stations, as well as a complete revolution in equipment. He also constructed thirty-six miles of new and heavy line, reflecting great credit upon himself, especially for his wisdom and energy in completing in time some heavy rock-cutting and bridging, when a failure as to time would have been equal to loss of franchise to the company.