A QUERY.

Evening Star, Issue 3740, 17 February 1875, Page 3

A QUERY.

To the Editor. Sir,—Could you or any of your read&s give me some practical rule by -which I could ascertain the number of gallons in a'Government head of water, as laid down by the Goldfields regulations. For the information of those who might feel inclined to reply, I subjoin the measurements The box is 12ft. in length, covered in on the top, and laid perfectly level; the box is also inserted into the upper portion of a weir or dam bank. The inside measurements of the box are as follows : 20in. by lOin. in the clear. A bar two inches in depth is {•laced across the bottom of the box at the outet, and a pressure board 6in. in depth is fastened in the box immediately above the bar, leaving an opening 20in, by 2in. for the escape of the water,” This constitutes a Government head of water. I confess that I have, tried all the formula that I could come across, and with a widely different result in every case. I subjoin a few well-known engineers’ opinions upon this subject:— Mr Simpson, in his report upon the Naseby Sludge Channel, estimates a head of water at 90 cubic feet per minute. . Mr J- Arthur Phillips, in his work on “Mining and Metallurgy,” describes a Californian miner’s inch of water as 947 cubic feet in ten hours; it having the same uniform pressure of 6in. ; as the Government head in New Zealand, it naturally only requires multiplying by 40 to bring it to the same denomination, and this is about (5.3 cubic feet per minute. t Millar < F.S. A., in reporting to Mr J. T. Thomson on the Tuapeka water supply, describes a head of water as 75,000 gallons for eight hours, which is equal to 25ft per minute, taking the cubic foot to contain Gj gallons. With so much diversity of opinion amongst engineers upon such a small subject, it is not to be wondered at that I am somewhat confused. By the method which I have employed. I make the bead equal to 62.40 cubic feet per second ; but I do not know whether I am correct or not. , Trusting that I shall receive some information upon this subject, I am, kc., t. AquaFortis. Dunedin, February 10.