Abstract: A downdraft gasifier has a gas producer. The gas producer includes an introducing portion provided in an upper portion for introducing solid biomass fuel 4, an air inlet 17 provided in a central portion, a fire grate 14 provided in a lower portion, and a product gas delivery portion provided below the fire grate. In this gasifier, there are provided fire-proofball laid layers in which a plurality of metal balls 15 are disposed in layers on the fire grate substantially uniform, and a preheating unit (such as a burner) for preheating the fire-proof balls. The metal balls 15 are preheated in advance to a predetermined temperature ranging from 500° C. to 800° C. before the solid biomass fuel is introduced into the producer. After that, the solid biomass fuel 4 is introduced into the producer, and gas produced in the producer is delivered from a portion below the fire grate.

Abstract: A telescopic lens tube protector to be fitted on telescopically connected lens tubes of a monocular or binocular telescope for protecting same from shocks of collisional impacts or the like. The lens tube protector is arranged to enshroud the entire outer peripheries of the telescopic lens tubes and constituted by a cover case which partially contains a cushioning bag structure or structures or which as a whole is in the form of a cushioning bag structure containing a cushioning material in a sealed state.