He and four others (including Heron, the new head of Fort Nisqually) were out examining land near Fort Nisqually. Tolmie and Mr. Heron were on horseback and three others were on foot.
Tolmie's account is as follows:
Mr. Heron returned about 9 this morning to breakfast. Afterwards we mounted the north bank of Coe by the path & were occupied nearly all day in collecting specimans of the soil .... H[eron] and I on horseback. While thus engaged our three attendents, McKie, Brown & Peter Tahi, the islander, felt the earth under them shake violently at least twice. Brown first exclamed, & seemed much alarmed -- He & McKie were on their knees at the time & felt violently lifted up, the sensations of Peter I could not ascertain, Mr. H & I did not perceive anything remarkable -- this happened at 20 minutes from 2 ... which is not far wrong. On returning to the house we learn't that the shock had been felt there, the boards in the floor of the house rattling together. The Indians were much struck & said, 'The chief's [Heron's] medicine is strong, He has gone up the hill to shake the grounds.' In some quarter of the globe, perhaps the Almighty has wrought some dire devastations by earthquake, one of the most powerful & calamitous instruments of chastisement employed against Mankind. The steep & broken faces to Eastward of the islands in the sound render it probable, that they have been severed from the main shore by an earthquake."
This earthquake was not felt at Fort Vancouver on the Columbia River.