As the title indicates, this is a translation from English; the title page says it was published in London in 1754. I could not find the author or title of the work being translated in the "Prefazione" to Istoria degli stati. The WorldCat listing for the copies in two German libraries, including the Bayerische Staatsbibliothek, credits Jacques Philippe Laugier de Tassy as the author. His original work was in French:
Laugier de Tassy, [Jacques Philippe]. Histoire du Royaume d’Alger. Amsterdam: Henri du Sauzet, 1725.
There were later editions in French, an immediate translation into Dutch, a later German translation, and a Spanish translation sometime after 1750 with additional material by the translator (by then, the Spanish had conquered and were occupying Oran). Tassy was apparently a French diplomat sent to Algiers in 1724. I haven't found a record of an English translation of Tassy, but perhaps Istoria degli stati was a translation of
Shaw, Thomas. Travels or Observations Relating to Several Parts of Barbary and the Levant.Oxford: Printed at the Theatre, 1738.
Shaw said (p. 70) that by 1732 Algiers had only six ships of 36 to 50 guns left from the larger number the city had had in 1724.