Our readers are invited to contribute to this department, but no responsibility is assumed for the opinions expressed in these communications.

Letters for this department should be addressed to Editor of Amateur Work, 85 Water Street, Boston.

They should be plainly written on only one side of the paper, with a top margin of one inch and side margins of one-half inch.

The name and address of the writer must be given, but will not be used, if so requested.

Enclose stamps, if an answer is desired.

In referring to other letters, give the number of the letter referred to, and the date published.

Illustrate the subject when possible by a drawing or photograph with dimensions.

Headers who desire to purchase articles not advertised in our columns will be furnished the addresses of dealers or manufacturers, if stamp is enclosed with request.

<No. 9.) Humber Bay, March 3, 1902.

(a) Could an induction coil be used to ring a magnet bell one mile distant instead of a magneto-machine, using two batteries for primary?

(b) If the current going through the primary winding of an induction coil is two volts and three amperes direct current, would the results given by the secondary be different if the current was alternating at the same amperes and volts'?

I am pleased to say that the induction coil made from instructions in the magazine works finely. B. C.

(a) While never having tried to ring a bell over a long distance, by increasing the voltage with an induction coil I should think it could be done. A magneto-machine is better and no more expensive.

(b) The only difference in the current given by the secondary, as above stated, is that in the first case the curve illustrating the drop in voltage between impulses is sharp, while with the alternating current it rises and falls at about the same rate.

<No. 10.) Bristol, R. I., March 9, 1902.

In the correspondence column of the March number you state that for an induction coil giving a one-half-inch spark one pound of No. 40 covered magnet wire is required. This costs $20, which is more than a complete Ruhmkorff induction coil can be purchased for. I do not understand how this difference in price comes.

C. B. R

The coils you mention are probably imported German or French instruments, and usually are not made with covered wire, but with bare wire with thread between and shellac or some other insulating material used to replace the wire covering. It would not be advisable for any one who was not very experienced to attempt to make a coil in this way. The directions given in this magazine are those thought most likely to produce successful results and most suitable for the amateur.

(No. 11.) Boston, Mass., March 15, 1902.

Will you please publish a description and drawings of wooden works suitable for the clocks recently described in the magazine? A. S. W.

A descriptive article on wooden works for these clocks is now in preparation, and will be published as soon as completed.

(No. 12.) Toronto, Ont., March 10, 1902.

Where and at what approximate price can one procure the works for the clock described in the December number by John F. Adams ? I am building the frame, and desire to know where to get the works. F. C. S.

The best movement that can be purchased at low cost is probably the one made by the Seth Thomas Clock Company, Thomaston, Conn., No. 85A; cost, $7.50. It is eight-day, pendulum 391/2 inches, ten-inch swing, sixty beats, strikes the hours, twelve-inch hands, wood rod and two-pound ball. A letter to this firm will secure the name of the nearest jeweler handling their goods.

Sir W. H. Preece, formerly chief electrician to the British post-office, has been engaged for some time on the study of the magnetic influences upon the compass of the Manacle rocks, off the coast of Cornwall, Eng., upon which the steamships Mohegan and Paris were wrecked, and, as the result of his investigations, he states that if any navigator sets his compass from Cherbourg to the Lizard, without knowing the variations of the magnet that have occurred during the last five or six years, he would run upon the Manacles. The variation is bringing the needle nearer to the north pole, and in ten years it has varied a whole degree. A difference of a degree in a compass signifies an error of one mile in a course of sixty miles.

According to Electricity, an experiment designed to have an influence on the horticultural industry was recently made in California, where electricity was used as a pumping agent for irrigation. The experiment was a success in every respect, and it was announced at its conclusion that there would be an immediate extension of the electric wires throughout the whole Berryessa district. The experiment and the success attending it are believed to have solved the water question for orchards, as far as the Santa Clara Valley is concerned.