Built around 1901 by John A. Chisholm as a summer home, Mount Vernon stood facing the lake between Navy and Thomas Streets.

The barn, cow shed (everyone kept their own cow at that time), gardener's cottage (now 143 Front Street and originally the home of the McCorquodales (see Oakville and the Sixteen)), and barn were north of Front Street which divided the property.

The wide hall with its large fireplace was paneled in oak and the walls were decorated with the heads of the elk, mountain goats, etc., that were shot by John while he was on hunting trips in the Canadian Rockies. The third floor, designed as a ball room, made a grand play room for the children. When John died the walls had never been papered and Emelda, who continued to occupy Mount Vernon as a summer home, left them that way for as long as the house stood.

For a number of years, no members of the Chisholm family were residing in Erchless. At that time it was being rented out to other people and when the house was finally put up for sale in 1920, Emelda Beeler Chisholm was able to purchase the estate so that it would be kept within the family. Mt. Vernon was sold, the house was burned and the land was taken over by the town for taxes and added to what little remained of Lakeside Park. The gardener's cottage, the barn and the garden were bought by Hugh Pullen as a wedding present for his daughter Gwynneth upon her marriage to Ralph Young.