Websters 1828 dictionary has this to say about sabbath.
1. The day which God appointed to be observed by the Jews as a day of rest from all secular labor or employments, and to be kept holy and consecrated to his service and worship. This was originally the seventh day of the week, the day on which God rested from the work of creation; and this day is still observed by the Jews and some christians, as the sabbath But the christian church very early begun and still continue to observe the first day of the week, in commemoration of the resurrection of Christ on that day, by which the work of redemption was completed. Hence it is often called the Lords day. The heathen nations in the north of Europe dedicated this day to the sun, and hence their christian descendants continue to call the day Sunday. But in the United States, christians have to a great extent discarded the heathen name, and adopted the Jewish name sabbath.
Looks to me like usage of Sabbath to refer to the Lord's day is not indicative of one's view on the Sabbath. These sermons were most certainly given on the first day of the week.
