W. C. Houghton

The battery here described is of the pasted lead plate type and may be made of any desired capacity by using a greater or less number of plates. There are always an odd number of plates, three, five, seven, nine, etc., there being one more negative than positive. The "grid" or lead frame adopted, requires a mould, which may be of wood or iron. A wooden mould, if carefully used, will do for casting a number of plates, but if many are to be made it should be of iron. In this form of mould no machine work is necessary except a little drilling and filing. Whether the wood or the iron mould is to be used, the first step is to make it in wood, only one-half need be made for the iron one. and this is used as a pattern from which two iron •castings are made.

Cut out a piece of 1/2" pine board 5 1/3x6 1/4". Also make seven pieces of 1/4" pine 9-16 wide on the bottom, and bevel them off on each side at 45 deg., which will make the top about 1/8" wide. These should be very accurately made, as the success of the job depends on their fitting well.

Take one of these strips and fasten it on the large board 7-16" from the long edge, using small brads and glue. It should be put 9-16" from the lower end. In like manner put on four more strips parallel with the first, using one of the strips placed bottom side up for spacing them. The sixth strip should be planed off on the outer edge to a sharper angle than the others, leaving top as it was, but making the bottom only 3/8" wide, after which it is fastened like the others.

Seven brads should be used in each strip, placing the first one 5-16" from the end, and the others at equal distances of 5/8 ". When strips are in place cut six notches 3-16" wide at the top, and 1/8" wide at the bottom, crosswise through all the strips down to the board. This may be done with a back-saw, finishing with a knife and a strip of fine sandpaper held on a thin, beveled strip of wood. If the iron mould is to be made, the pattern is now complete, except that it should be given two coats of black shellac. If, on the other hand, it is to be used as a mould it should not be shellaced, but a second one should be made and a strip of wood J" thick and 2/3" wide, with the inner edge slightly beveled, fastened to the left-hand edge of one of them. Also make two blocks of i" wood shaped as shown in drawing to go at the top to make the lug and the pouring-gate. These should be slightly beveled on three edges to give draft to the mould, i.

e., to make the cast plate come out easily. The other half of mould should be the same, except a |" strip should be placed at the bottom and no blocks at the top. When placed face to face the halves should fit together all around, making a lead-tight mould. All that remains is to carefully sandpaper off the tops of the little pyramidal blocks, but not the sides and top, to a depth of 1-16", giving space for the metal to flow. If the work has been carefully done the maker is now ready for casting.

First, chalk the mould all over inside rather heavily. This helps prevent burning the mould more than necessary, and also makes the lead run more freely. The wood of the mould should be as free of pitch as possible. Next melt the lead, but take great care to have it hot enough to run freely. This is important. Clamp the mould together with wooden hand screws, place upright and pour as fast as possible without spilling. The whole secret of running lead is to get the metal in quickly, before it has a chance to freeze. After taking out the plate and re-chalking mould, you are ready for casting another. As many as twenty plates can sometimes be cast from one wooden mould.

If the iron mould is decided upon, take the wooden pattern to the foundry and have two castings made from it. Lay one casting face up on the bench, put on some coarse emery and grind the other one to a fit, using water and sliding one plate back and forth till they come together. This will take an hour or two, according to how well the pattern was made. When fitted, file off 1-16" from the face of each half, leaving the pyramids 3-16" high. If the cross notches need a little fitting, that may also be done with a thin file. The mould is then to be finished like the wooden one, by riveting iron strips on sides and top of one and side and bottom of the other.

The iron mould is to be warmed and then heavily smoked with a candle or lamp before casting. The lead should be hotter than for the wood mould, as it will run better. The positive plates will be better if a little antimony, say 1/4 oz., is added to every pound of lead. When you have moulded a sufficient number of plates you are ready to paste them. Each plate will require about 6 oz. of lead oxide. Use red lead or minium, for the positives, aud yellow lead, or litharge, for the negatives. The paste is a kind of mortar made by moistening the lead oxide with a ten per cent solution of sulphuric acid. To mix the acid put a sufficient quantity of water in an earthen jar and add 1-10 the quantity of acid, pouring slowly and stirring with a strip of glass. Bo not pour water into acid. Mix the lead oxide to a very stiff paste with the acid water, and using a thick piece of glass or a wooden paddle for a trowel, plaster one side of the plates, working the paste well into the holes. Turn over and finish the other side in the same way. Scrape off all surplus paste and put away to dry.

To assemble the battery, cut pieces of burlap of the right size to cover the plates all over except the lug on top, and with coarse cotton cord cover plates tightly, sewing firmly around three edges. The burlap is to be folded over the fourth edge. Next take some sheet lead 1-8" or 3-16" thick and cut out two lug connectors for each cell, as shown in drawings. Next make eight strips of pine wood for each cell 1/4 x 1/4" and 4 1/2" long. Lay a negative plate on the bench with the lug on the left. Put a wooden strip on each edge. Lay on a positive plate with a lug to the right, then more strips, negative plate, strips, positive plate, and so on, until you have as many as you wish. Three plates will give a capacity of 10 to 12 ampere-hours; five plates, 15 to 20; seven, 25 to 30, and so on. The voltage will be same, no matter how many or how few plates are used, namely, about 2 1/2 volts on open circuit and 2 volts when using normal current. The normal charge or discharge rate is 1-8 to 1-10 of the capacity : that is, the 15 ampere-hour cell should ordinarily be charged or discharged at the rate of 2 amperes and would last about 8 hours at that rate.

When plates are grouped as above, put two or three heavy rubber bands around them and turn the bunch up on end. Fit the lug connections on with the ends pointing outward. Solder them in place, taking care-not to overheat and melt the lead. Bend outer ends upward, and your battery is ready to put in the jar of acid and charge. The acid should be about one part sulphuric acid to five of water.

Do not put plates in acid after mixing till it is cool. The jar may be of hard rubber or glass. Suitable jars may be purchased, but are rather expensive. A glass jar of the right size for the five plate cell costs 50 cents. An ordinary round telegraph battery jar, costing only 25 cents, will do; or a large glass bottle may be cut off at the right height, which should be about six inches. The acid should cover the tops of the plates to depth of at least J". Evaporation of the solution may be prevented by pouring melted paraffine wax on the top of jar to a depth of J". Two or three small holes should be made in the wax to allow gas to escape when charging the battery.

The battery may be charged from any source of direct current. Alternating current will not do. About 2 1/2 volts per cell will be required. A small dynamo is the best thing for the purpose if power is available-Begin the charge of 15 ampere-hour cells at the rate of 4 or 5 amperes. This rate is to be reduced as the charging proceeds, ending with about half an ampere, which should be continued for six or eight hours, the first few times. The battery will not attain its full capacity till it has been charged and discharged a number of times. This process is what is called forming.