_To test battery._--It is necessary to do this periodically, as if the battery is not showing a sufficient number of ampères the car will run badly. The test is made with an ammeter (provision for which has been made in the list of spares), the positive points making contact with those corresponding on the battery, the ampèrage being registered on a small dial. It should always show four or over. When it gets below this point it is advisable to carry a spare battery, as a stop on the road through a battery giving out is annoying, and a battery cannot be procured at every repairer’s. _Empty petrol-tank._--If the car comes to a standstill after a few misfires, it may be caused through the petrol-supply being exhausted on account of the tank having sprung a leak or the petrol merely being used up. The former is a very unusual occurrence, rarely occurring on a car with the petrol-tank under the seat. Where the tank is placed at the back of the frame of the car it is often punctured by a sharp stone striking it. Always, if going any distance, carry a spare can of petrol and a funnel, and before filling the tank be quite sure that there is no dust in the funnel or on the top of the can, as the smallest quantity of dirt will choke your petrol or carburetter, and this takes a long time to remedy. _Choked petrol-pipe or carburetter._--You may possibly believe at first that this trouble is caused by the petrol running out, so look in the tank, and if it contains petrol you may be sure that the flow is checked in some way. “Agitate” the float of the carburetter and it will most likely be found that there is no petrol coming through, therefore there must be a stoppage between the tank and the [Illustration: _Photo H. W. Nicholls._ IT IS A SIMPLE MATTER TO ADJUST THE TREMBLER OR SCREW] carburetter. At the bottom of the carburetter there is a little joint, connecting the carburetter with a small tube through which the petrol is carried. See first that the petrol-supply is turned off, then loosen the joint and take out the pipe, then turn on the petrol and see if it comes through as far as that. If it does, the trouble must be in the carburetter jet. It is a simple task to remove this with the carburetter jet spanner, and an ordinary hairpin would then remove every obstacle. _Water in carburetter._--This may sometimes cause the engine to run badly, and is not an unusual occurrence. On the top of the carburetter being removed the water will easily be noticed. It is heavier than petrol and the little drops of water in the petrol look like drops of lead. In order to guard against suspected water you can filter the petrol through a handkerchief laid in the funnel.