shaft?-Father: They may; as the amount of air produced for the workings will be just the same, if fixed at one or at the other. You know a pound of pressure, added or diminished, is like the scales one and the same. Yet the steam, no doubt, would affect the workings if the jet were fixed at the top of the down-cast.

Son Suppose you had a ventilating fan, at which shaft would you fix it?-Father: If possible, I would fix it at the top of the downcast.

Son: But why; when the same quantity of air is produced at one as well as at the other shaft?-Father: I know the quantity of air for the workings would be the same, but there would be less danger of filling the workings with explosive gas.

:

Son Filling the workings with explosive gas? Why, how can a ventilating fan fill the workings with gas?-Father: You know I have stated before, that gas is pressed or pent-up in the strata by the great weight of the atmosphere; therefore, anything that takes away the weight which presses the gas in would let the gas out, like letting out steam from a boiler, by taking off the weight off the valve. Now, in case a ventilating fan were fixed at the top of the up-cast to propel air out of a mine, if the air passage between the shafts suddenly closed up, every stroke of the fan would empty out that air which pressed in the gas, by which the mine would suddenly fill up with gas, and cause, no doubt, great loss of life.

Son: Do you think it would not fill, then, with gas, if fixed to force air into the down-cast? Father: No; because every stroke of the fan would press a greater weight upon the pentup gas, and give more time for the men to escape the danger.

Son: It requires, I see, much caution and care, and also a person with a good foresight, to prevent loss of life in mines. But I fully expected to have had, father, before this, a little conversation how gases are conducted by air through and around the workings in mines.-Father: It it my wish to impress on your mind, and also on every miner in the kingdom, things that will do good for years to come; therefore, as you have a knowledge how air is made to pass down into a mine, we will have a little conversation now how air is made to pass several ways in and through the workings of a mine.

Son: Will you be able to show how air passed around Lund-hill workings, where 189 lives were lost, and at Risca, and at all those places where great numbers have been lost; and also show a better way to prevent loss of life?-Father: Yes; I shall be able to show the mode of ventilation at those places, and also a better way.

Son: Did you not show the mode of ventilation at Lund-hill which caused the four months' discussion in the public papers between you and the late John Wales, Esq., viewer in the north of England?-Father: Yes; poor Mr. Wales, I was sorry to hear of his death. The north people lost a valuable man when he died; he was a man with a good knowledge of mine ventilation. He did not charge me with not showing properly the mode of ventilation at Lund-hill, or the improved mode, but he had a notion I had made an error in the non-fixing of a regulator.

Several Modes or Ways of Ventilating Mines.

Son: You have a plan, I see, showing the mode of ventilating and working of mines. Where is this mode of ventilation

adopted?-Father: In all mines where great loss of life has been caused by explosions.

Son: Was this the mode of ventilation adopted then at Lund-hill, where one hundred and eighty-nine persons were killed by that dreadful explosion, and also at Risca, where more than one hundred and forty were lost?-Father: The plan you see shows the mode of ventilation on the south levels at Lund-hill; and the supposed place of the explosion was at or near the No. 24 (see plan); some supposed the place of the explosion to have been at the furnace, where the whole quantity of gas from all the workings passed through, as the power or shock of the explosion spread, and affected north and south at one time.

Son: Were there not many doors at Lund-hill? I understand there is always much danger where many doors are in mines.-Father: There were 52, just as many as there are weeks in one year. There are always a great number of them where this mode of ventilation is adopted.

Son: Do the arrows on the plan show the route of the air from the down-cast into and around the workings to the up-cast ?-Father: Yes. You see the arrows show the passage of the air; it commences its route at No. 1, from there it travels on the south level to No. 2, from there to No. 3, from there back to No. 4, then onward to No. 5, back again to No. 6, from there onward to one of the working faces at No. 7, then it is conducted back to No. 8, from there to the face of one of the narrow workings at No. 9, it then returns to No. 10, from there to the face of another working place at No. 11, then it returns to No. 12, it then enters the narrow working face at No. 13, and comes back again to No. 14.

Son: Well, father, what a great route air travels by this mode of ventilation.-Father: Yes, and if the route extended as far, from the down-cast through the workings to the up-cast, as one end of the river Nile is far from the other, go it must if only it can travel. There is no alternative with some managers but one continuous route conducting explosive gases into every part of a mine.

Son: By passing air backwards and forwards into and out of the working places there must be a large quantity of gas collected in the air long before it discharges itself at the top of the up cast. The air has yet to travel in and out from No. 14 to Nos. 22 and 23.-Father: At No. 22 (see plan) the gases accumulated in the air from all the workings in the north part of the mine meet the adulterated air from the south; at that place the two currents join. Afterwards this large adulterated current passes through a blazing fire or furnace at No. 23.

Son: Is this mode of very ancient origin?-Father: It was first adopted by our great grandfathers in the early days of coal mining, and, I am sorry to say, handed down from one generation to another, as it exists at the present day.

Son: Is there no improvement to be made for the better and safer working of mines, and, if so, why keep to so great a lifedestroyer?-Father: There are improvements in mine ventilating as well as in all other things, yet I cannot tell why the improvements are not adopted, unless managers wish not to give up what was left them by their ancestors; or, their knowledge of mine ventilation may only consist in what was well known in the early days of mining.

Son: If that mode of ventilation is adopted we may well have, and also expect, great loss of life and property. I fear