original passage: American George B. Grant started working on his calculating machine in 1869, unaware of the works of Babbage and Scheutz (Schentz). One year later (1870) he learned about difference engines and proceed to design one himself, describing his construction in 1871. In 1874 the Boston Thursday Club raised a subscription for the construction of a large-scale model, which was built in 1876. It could be expanded to enhance precision and weighed about.
original sentence: Grant started working on his calculating machine in 1869, unaware of the works of Babbage and Scheutz (Schentz).
sentence2: Was the works of Babbage and Scheutz (Schentz) not known by Grant?
sentence1: American George B. Grant started working on his calculating machine in 1869, unaware of the work of Babbage but aware of work of Scheutz (Schentz). One year later (1870) he learned about difference engines and proceed to design one himself, describing his construction in 1871. In 1874 the Boston Thursday Club raised a subscription for the construction of a large-scale model, which was built in 1876. It could be expanded to enhance precision and weighed about.