A castor includes a body, a wall of a rotary bearing, a wheel including an orifice, a rotary shaft, elements for mounting the shaft to co-operate with the bearing wall, the latter having a first bearing wall portion of tuning-fork-shape defining a slot between two limbs and another bearing wall portion having a base and a tenon secured to the base, the tenon may be engaged in the slot. The condensing step may be carried out with a metal salt under basic conditions. Other suitable emulsifiers together with glycerine and essential or vegetable based oils with or without inorganic fillers may also be added to the jelly to impart fragrance, color, UVA and UVB sun protection factor, immuno-enhancing aromatherapeutics, as well as free radical scavenging constituents. This invention also discloses a fluid machine for conveying, compressing or expanding liquid or gaseous fluids, which includes a casing comprising a housing, an upper end cover and a lower end cover. The beams instead are pivotally mounted directly on the main members.