Tire placard pressure is often much lower than listed on the tire sidewall. Air pressure given by the vehicle maker was based on the tires supplied with the vehicle. They design many newer replacement tires to give a good ride, with much more pressure.
Fresnel lens. A Fresnel lens is a type of lens invented by Augustin-Jean Fresnel. Originally developed for lighthouses, the design enables the construction of lenses of large size and short focal length without the weight and volume of material which would be required in a lens of conventional design. Detailed information.
How to use a camera lucida. The camera lucida is generally considered to have been invented by the English chemist W. H. Wollaston in 1806-07, although there is some speculation that it is a reinvention of a device described by Kepler some 200 years earlier.