No. 70. Philadelphia, Pa. Jan. 18, 1904.

I would like to know if you could give the approximate cost of building the sailboat described by Carl H. Clark in the Jan. '04, issue. Also, if a gasoline engine could be placed in the boat, as an auxiliary, without very great change in the boat.

G. G. M

The cost of materials will vary with the locality; between $30 and $40 for the lumber, exclusive of spars. Metal work, about $10. Sails and rigging $15 to $25 according to quality.

A small engine could be installed by cutting away a piece of the deadwood aft, using a balanced rudder, and making water-tight around the shaft where it passes through the keel. The engine would have to be placed in the cabin, or extreme forward part of the standing room.

No. 71. Schenectady, N. Y., Jan. 31, '04.

I would like to know if it is possible to obtain a set of castings for the model steam turbine described in the January number?

J. J

No castings for this turbine are obtainable in this country, the description being of one made in England. Should a sufficient number of our readers make requests for these castings, they will be offered as a premium.

No. 72. Bridgeport, Conn., Jan 30, '04.

I wish to know if there is any storage battery which will supply current to light six or seven incandescent lights in a satisfactory manner. If so, please tell me where to get them, and the chemicals for charging ?

H. F. P

Your inquiry does not state the size and voltage of the lamps you desire to use. If miniature lamps of 3 or 4 volts are intended, storage batteries are to be had which will do this nicely, of any large dealer in electrical supplies, but the expense for same will be considerable. They will also have to be charged by current from a dynamo, unless another set of cells of another type are obtained for charging, the latter being a rather unsatisfactory way. The Pullen cell manufactured by the Pullen Electric Co., Chestnut St. Philadelphia, Pa., is a cell which may be charged by chemicals, and recharged, when exhausted, in the same way. Twelve to fourteen of these cells would be required for the work above mentioned.

No. 73. Providence, K. I. Jan. 30, '04.

Will you kindly inform me what the electrical resistance is of No. 23 guage German Silver wire per foot. Will you please tell me of some firms who make wood turning lathes? P. H. F.

German silver wire varies considerably in the proportions of its constituents, and consequently the resistance would vary from the same cause. The resistance for 1000 feet, standard quality would be approximately 271.6 ohms. If great accuracy is required for some electrical instrument, the resistance should be obtained by testing with suitable instruments. These can be found at most electric light stations, and those in charge will usually render services of this kind if approached in a suitable manner.

Turning lathes are advertised in our advertising columns by several firms who will send catalogues upon request.