The boys frequently discussed possible combinations in this system. I spent a great deal of time loafing around among them in a comatose condition, and they talked quite as freely when I was around as when they were alone among themselves. One day I heard Dyne say, "Suppose we should store in a reservoir the water which comes down the penstock during a day and store all the electricity it will generate in a day in a storage battery, then at night let the battery run the dynamo backward as a motor, and that turn the water-wheel backward as a rotary pump, we should have the water in the upper reservoir to begin work with the next morning and the problem of perpetual motion would be solved.
"Aw, why do you want to do all that," said Erg, "when nature is doing it for us?"
Ernest said he had a better scheme than that. He would turn the battery current on to all the motors in the room and they would run the counter shafts forward and the counter shafts would run the dynamo forward and the dynamo would charge the battery, and so you could keep up the motion perpetually if you wanted to.
"Get out your pencils," said Harold, as he took down a copy of Houston and Kennelly. "Let us see how we would come out if we tried Dyne's proposition for, say, twenty hours, storing the energy from the falling water for ten hours in the battery and then using this energy during the next ten hours for re-storing the water in the upper pond. We will say that the water-wheel furnishes eight horse-power for ten hours—eighty horse-power hours."
I notice it is stated in this book that small dynamos are usually unable to deliver more than 75 per cent. of the energy impressed upon them, and storage batteries and motors deliver about 80 per cent. of the energy impressed upon them. The accounts would, therefore, stand as follows:
| Dynamo | Horse-power Hours | |
| Dr. | Cr. | |
| To energy impressed by water-wheel | 80 | |
| By energy delivered to storage battery | 60 | |
| By loss in heat | 20 | |
| ———————— | ||
| 80 | 80 | |
| (Assuming that the battery was able to receive all the dynamocould give.) | ||
| STORAGE BATTERY ACCOUNT | ||
| To energy impressed by dynamo | 60 | |
| By energy delivered back to dynamo running as motor | 48 | |
| By loss in heat | 12 | |
| ———————— | ||
| 60 | 60 | |
| Dynamo Running as Motor | Horse-power Hours | |
| Dr. | Cr. | |
| To energy impressed by battery | 48 | |
| By energy delivered back to water-wheel | 36 | |
| By loss in heat | 12 | |
| ———————— | ||
| 48 | 48 | |
| (This dynamo being a particularly inefficient motor.) | ||
We cannot give the account of a water-wheel acting as a pump, because such a machine has not yet been perfected. It is evident however that if a water-wheel could be devised that should be a perfect pump, the losses in this chain of machinery are more than half; indeed, the accounts show them to be 60 per cent. We should, therefore, be able to return less than half the water drawn from the lake each day, and we should rapidly move toward bankruptcy.
"Well," said Ernest, "my proposition is more successful than that, because it sets out to be a fool proposition."
It was first suggested by the snake who undertook to swallow himself. Suppose the account does taper down from eighty to one, so does the snake, but he still remains "wise as a serpent." Our account would stand as follows: