Famous for his discovery on hydra, Abraham Trembley was also much interested in the devices he used for his scientific investigation. Particularly, he conceived instruments that could best fill the needs of his research, among them, microscopes. When in London in 1745, he got in touch with the instrument maker John Cuff and asked him to build a microscope with an eyepiece that could move in all directions. In other words, Trembley invented aquatic movement and Cuff made the instrument for him. However, Trembley never claimed his invention, therefore we used a contextual approach to reconstruct this story. We investigated his relationships with the world of practitioners, his role as an agent for buying instruments for his patron William Bentinck, and, through his unknown correspondence with Martin Folkes P.R.S., we could identify his authorship with certainty. As a consequence, the microscope he invented is the ancestor of the socalled Cuff-Ellis microscope, that originated in Trembley's model.