Well, It is an "Atlantic" class locomotive. Judging from the chipped paint it is either brass, or cast metal with brass fittings. My guess would be in the straight brass category. Looks old based on the monster headlight and jewel marker lamps.
So, might try looking in the "The Brown Book of Brass Locomotives". I believe they have historical lists by loco class and manufacture. Mine is packed up in a box somewhere or I would take a gander for you.