He could handle dogs and sledges.

He was a part of the traveling machine.

Had I taken another member of the expedition also, he would have been a passenger, necessitating the carrying of extra rations and other impedimenta.

It would have amounted to an additional load on the sledges, while the taking of Henson was in the interest of economy of weight.
The second reason was that while Henson was more useful to me than any other member of my expedition when it came to traveling with my last party over the polar ice, he would not have been so competent as the white members of the expedition in getting himself and his party back to the land.

If Henson had been sent back with one of the supporting parties from a distance far out on the ice, and if he had encountered conditions similar to those which we had to face on the return journey in 1906, he and his party would never have reached the land.