What was advertised in a colonial American newspaper 250 years ago this week?

“The List of Subscribers will be committed to the Press in a few Weeks.”
When John Dunlap set about publishing “ALL THE POETICAL WRITINGS, AND SOME OTHER PIECES, OF THE REV. NATHANIEL EVANS” at “the Newest Printing Office in Market-Street, Philadelphia,” he looked beyond the city in his efforts to cultivate customers. On August 29, 1771, he advertised the book in the Massachusetts Gazette and Boston Weekly News-Letter in hopes of selling copies to readers in New England. In so doing, Dunlap pursued marketing practices already familiar in the colonies. In the eighteenth-century, American printers often distributed subscription notices for their projects. They inserted advertisements in newspapers published in multiple cities, inviting “subscribers” to order copies in advance. Some supplemented those advertisements with handbills and circular letters. Others even printed forms with blanks for local agents, usually booksellers and printers, to fill in the names of customers who reserved copies.
In recognition of their commitment to a project, subscribers received a premium in the form of having their names published. Printers marketed subscription lists as valuable items intended to be bound into books along with title pages, frontispieces, tables of contents, copperplate engravings, indexes, and other ancillary materials. Each subscription list represented a community of readers and benefactors who supported a project. Within those printed lists, subscribers found themselves in the company of others who shared their interests, gaining status through the association. Those who chose not to subscribe missed opportunities for public acclaim. For his part, Dunlap made it clear that prospective subscribers had only a limited time to see their names among the ranks of those who supported “THE POETICAL WRITINGS … OF THE REV. NATHANIEL EVANS.” Even though the book already went to press, he had not yet printed the subscription list. Instead, he warned that “the Lost of the Subscribers will be committed to the Press in a few Week” so “all who are desirous of encouraging this Publication, and who may not yet have subscribed” should “sent their Names, without Loss of Time” to his local agents in Boston. Dunlap sought to create a sense of urgency to convince prospective subscribers to submit their names and commit to purchasing copies of the book.