People who lived on the island, and their friends and relatives, would have their own ways of getting across the harbour back then just as they do now. So this notice was directed at potential tourists -- guests -- who would stay at the island's hotel. It's intriguing to wonder who would have visited back then, and why they came. I imagine they came to see the lighthouse, or just for the adventure of visiting an offshore island. At any rate, the McNutt's Island Hotel & Excursion Company could promise them a few days in a delightful spot.
And even in the olden days, before cell phones, there were clever ways to communicate.
Thanks to Kim Robertson Walker, Archivist at the Shelburne County Archives & Genealogical Society, for sharing this notice.