1. How many of these electrical appliances we would be likely to use at one time. 2. How much current each device would require. 3. How much they must allow for losses in generating the current, in transmitting it, and in transforming it. We assured them that we would never use more than twenty amperes, say, two thousand watts at one time. They might install a fuse, or circuit breaker in our line to protect their plant against a greater load from us. I told them that they might allow 20 per cent. loss of energy at the dynamo in converting water-power into electric-power. I would suggest generating their current at 115 e. m. f. and stepping it up to 460 for transmission to us, and then stepping it down to about one hundred and ten volts for our use. They might count on about one-third loss on our supply, that is, they would need to generate about three thousand watts in order to deliver us 2000 watts. I suggested making our line of No. 6 copper wire, which has a resistance of two ohms to the mile. The distance from the mill to the cottage is one mile, and the complete circuit therefore would require two miles of wire, or four ohms of resistance. If we start with 3000 watts and lose 14 per cent. in transforming we shall have 2580 watts to transmit. If the voltage has been stepped up fourfold there will be about 5.6 amperes to transmit which will suffer a loss of 22.4 volts in passing through four ohms of resistance on the line. The loss in transmission will be about 5 per cent., and we shall have on arrival at the cottage about two thousand four hundred and fifty watts with a voltage of 437.6. If now in stepping this down to one fourth the voltage, viz., 109.4, we lose 14 per cent., we shall have left something over two thousand one hundred watts, or nearly twenty amperes. Assuming that you are able to generate 4800 watts of electricity and that 3000 watts must be furnished for transmission to the cottage, you have left 1800 watts, which will give you something over fifteen amperes at 115 volts for use in your machine shop. I suggest that we get a dynamo which will generate both alternating and direct current--the alternating current you will send to the cottage, and the direct current you will have for use at the machine shop. But how is it possible for a dynamo to generate both alternating and direct current at the same time? [Illustration: Fig. 138] [Illustration: Fig. 139]