He developed the first reflecting telescope, which featured a concave mirror, a flat mirrow & an eyepiece
The 
reflecting telescope was invented in the 17th century as an alternative to ... A 
curved primary mirror is the reflector telescope's basic optical element that 
creates... [DOC] [TLE] History of the telescope - Wikipedia [PAR] The earliest known working telescopes appeared in 1608 in the Netherlands and 
are credited ...