On physical properties of solar spicules

New observations of solar spicules at Pulkovo, made simultaneously in 4 spectral regions, are described. The profiles of the H, D3, H, H and K lines were derived for 23 spicules.The spicules occur usually in narrow bundles and can be resolved into separate objects only due to a dispersion of radial velocities inside the bundle. The spicules in D3 are diffuse with faint interspicular emission.The emission of hydrogen, helium and Caii originate in different parts of spicules with different radial and turbulent velocities. The core of a spicule with Caii emission is a narrow rope several tens of km in diameter for the normal section. The optical thickness of a spicule in H is approximately 1.0 and the atomic density varies from 10¹¹ to 10¹² cm^–3.The helium emission in spicules seems to be produced by different mechanisms, one of them being the external radiation of corona and subcoronal matter.The model of a solar spicule is discussed.