parts.

_Don't_ fail to adjust the B battery after putting in a fresh vacuum tube, as its sensitivity depends largely on the voltage.

_Don't_ fail to properly space the parts where you use variometers.

_Don't_ fail to put a copper shield between the variometer and the variocoupler.

_Don't_ fail to keep the leads to the vacuum tube as short as possible.

_Don't_ throw your receiving set out of the window if it _howls_. Try placing the audio-frequency transformers farther apart and the cores of them at right angles to each other.

_Don't_ use condensers with paper dielectrics for an amplifier receiving set or it will be noisy.

_Don't_ expect as good results with a loop aerial, or when using the bed springs, as an out-door aerial will give you.

_Don't_ use an amplifier having a plate potential of less than 100 volts for the last step where a loud speaker is to be used.

_Don't_ try to assemble a set if you don't know the difference between a binding post and a blue print. Buy a set ready to use.

_Don't_ expect to get Arlington time signals and the big cableless stations if your receiver is made for short wave lengths.

_Don't_ take your headphones apart. You are just as apt to spoil them as you would a watch.

_Don't_ expect to get results with a Bell telephone receiver.

_Don't_ forget that there are other operators using the ether besides yourself.

_Don't_ let your B battery get damp and don't let it freeze.

_Don't_ try to recharge your B battery unless it is constructed for the purpose.

STORAGE BATTERY DON'TS

_Don't_ connect a source of alternating current direct to your storage battery. You have to use a rectifier.

_Don't_ connect the positive lead of the charging circuit with the negative terminal of your storage battery.

_Don't_ let the electrolyte get lower than the tops of the plates of your storage battery.

_Don't_ fail to look after the condition of your storage battery once in a while.

_Don't_ buy a storage battery that gives less than 6 volts for heating the filament.

_Don't_ fail to keep the specific gravity of the electrolyte of your storage battery between 1.225 and 1.300 Baume. This you can do with a hydrometer.

_Don't_ fail to recharge your storage battery when the hydrometer shows that the specific gravity of the electrolyte is close to 1.225.

_Don't_ keep charging the battery after the hydrometer shows that the specific gravity is 1.285.

_Don't_ let the storage battery freeze.

_Don't_ let it stand for longer than a month without using unless you charge it.

_Don't_ monkey with the storage battery except to add a little sulphuric acid to the electrolyte from time to time. If anything goes wrong with it better take it to a service station and let the expert do it.

EXTRA DON'TS

_Don't_ think you have an up-to-date transmitting station unless you are using C.W.

_Don't_ use a wire from your lightning switch down to the outside ground that is smaller than No. _4_.

_Don't_ try to operate your spark coil with 110-volt direct lighting current without connecting in a rheostat.

_Don't_ try to operate your spark coil with 110-volt alternating lighting current without connecting in an electrolytic interrupter.

_Don't_ try to operate an alternating current power transformer with 110-volt direct current without connecting in an electrolytic interruptor.

_Don't_--no never--connect one side of the spark gap to the aerial wire and the other side of the spark gap to the ground. The Government won't have it--that's all.

_Don't_ try to tune your transmitter to send out waves of given length by guesswork. Use a wavemeter.

_Don't_ use _hard fiber_ for panels. It is a very poor insulator where high frequency currents are used.

_Don't_ think you are the only one who doesn't know all about wireless. Wireless is a very complex art and there are many things that those experienced have still to learn.

THE END.