 Starting from these metaphysical questions concerning the foundations of physics, Bolzano then occupied himself in several works also with concrete questions in natural science (e.g. in Bolzano 1842, 1843c, and 1851), and in particular with physical and astronomical questions. Although he was not able to aim at new and enduring results in these areas, his writings nonetheless show that he was also seriously occupied with such questions and could be “conversant” in the status of these disciplines during his day. To be mentioned here are especially his work on the composition of forces (Bolzano 1842) and two essays in the Annals of Physics and Chemistry, in which he was concerned with the writings and theories of Christian Doppler (Bolzano 1843a and 1847). A summary of Bolzano’s contributions to the philosophy of nature and to physics can be found in Berg 2003.