One of the most successful types of such heating lamps, and which has overcome the difficulty of smoke and smell, depends for these results upon the main fact that the air necessary for the burning flame is supplied to it on both sides of the flame, and in ample quantity. This is effected by using a wick that is woven in the form of a hollow cylinder, and so arranging the burner that air is freely admitted up through the space through the centre of the wick, to the top lit portion. At the top it is baffled by a cap so that the air turns at right angles over the top of the flame, thus meeting air and flame at the flame position. Provided that air is freely admitted through the centre of the wick, and also round the outside, then no smoke is given off, provided of course that the wick is not allowed to get charred, and is kept to a reasonable straight edge, etc.

As paraffin has a smell, it is necessary to ensure that no part of the outside of the lamp has any trace of paraffin upon it, only two precautions are necessary to avoid this (a) wipe every part of the lamp body, keeping it clean and dry, and (b) when the lamp is out, then keep the wick turned down into the body, otherwise since paraffin " creeps " freely, it will when the wick is turned up (but not lit), creep down the outside of the wick-holder and when warmed will give off a strong smell.

The wick, as in all other lamps, requires to be given some attention, but in these lamps a rub round the top of the wick (when brought just level with the top of the wick-holder, with a piece of paper, will do all that is required, unless the wick has been allowed to get charred, due to absence of oil.

.Most of these lamps have a device to show the oil level in the oil container, without having to open it. This is generally done by a small finger that points around a dial graduated from "O to Full," with positions marked as 1/4, 1/2 and 3/4. This device is generally worked by a small hollow metal float, which works the needle through a toothed quadrant and pinion. Sometimes these get out of order, and then require attention. If it does not register but will do so when the needle is given a start by a touch with the finger, then it is apparently simply sticking; take the whole out (the dial cap comes out like a cork, bringing the rest of the gear with it), examine carefully, the trouble should easily be seen and put right. If, however, the finger on the dial can be moved freely round by hand (when it was in the lamp), but always goes back to zero on the dial, then it means that the hollow metal float has leaked and is more or less full of paraffin. The best way to proceed is to drill a small hole say 1/32in. or so in diameter, at both ends, and blow hard at one end, the oil will come out freely at the other drilled hole. Before doing this, however, an attempt should have been made to discover the existing leak, generally a slight " weep " will be seen if it is wiped carefully, and watched closely. Solder up the leak, and the two drilled holes, and replace, taking care that the float does not rub against the inside of the lamp body.

The whole of the outside of the oil container in lamps having a metal body should be examined carefully from time to time to see whether there is any sign of a slight leak, shown by a wet surface; solder well if any be found. The oil, by reason probably of some impurities in it, does sometimes attack the oil container if of iron, and for this reason some of these lamps have brass oil containers.