Lewis never did write in his journals about just why he selected a Newfoundland Dog to accompany him on his epic journey across North America.  Maybe he read about the dogs in Sir Thomas Bewicks 1790 publication, "British Quadrupeds" where Newfoundlands were first described as a separate breed.  Their reputation was for great size, strength, docility, sagacity, and natural ability in water with their web feet.

    "Seaman" was probably born a black pup, maybe even in newfoundland, in 1802.  He was purchased by Lewis for $20.00, possibly in Baltimore.  he is often mentioned in journals throughout his epic adventure, but first in 1803 by Lewis as he took his keel boat, or prologue, down the Ohio River from Pittsburgh to Fort Dubois, just north of St. Louis.  It was here that the Corps of Discovery gathered to embark on their historic trip in May 1804, with 46 men, 4 horses and one Newfoundland Dog.

    "Seaman" was far more than a pet or a mascot.  He was an integral member of the "Corps of Discovery."  As the reporter Charles Collins of the Chicago Tribune wrote, " Seaman had been the life of the party, helping retrieve game, killing deer, chasing buffaloes out of camp, and keeping watch for grizzly bears."  He was truly as author Lord Byron wrote of his Newfoundland Dog, "Boatswain" in 1808, "beauty without vanity, strength without insolence, courage without ferocity, and all the virtues of man without his vices."

    "Seaman" was a dog of noble substance.  he was probably 150 pounds and stood about 30 inches at the shoulders.  But apart from his imposing size, he was also a major asset to Lewis and Clark in their talks with Native Peoples by virtue of his personality. When Lewis met with the Shoshoni relatives of Sacajawea, he needed their help to obtain horses and a guide to to get them across the Rocky and Bitterfoot Mountains.  He found Seaman to be of major help with these negotiations.  he wrote in his journal, "Every article about us appeared to excite astonishment with their minds; the appearance of the men, their arms, the canoes, our manner of working them, the black man York, and the sagacity of my dog."