and other things, so that no general rule can be given.

If the ridger is not heavy enough with a man on it, it may be weighted with sacks of earth. When dragged over loose earth with the large opening forward, this will throw the earth to a ridge in the center behind. On rebellious ground, and often on any ground, it is advisable to have two ridgers, one larger than the other running ahead to gather earth, the other attached immediately behind to concentrate it. But to work well, this, or any other form of scraper, must have the ground in fair condition from harrowing

from either side there will be openings to be filled with the hoe. This is not as much of a task as it would seem, and for some work you may so arrange the lines according to the slope of the ground that you can use those places to let the water from one check into the one below it and thus not have to fill it so completely.

TURNING IN THE WATER.

When all is ready, the head of water is turned in and divided among as many tiers of checks as can be comfortably handled at a time. If the stream is too large for the number of checks, it will

or plowing, and sometimes both. If the ground is hard or tough the plow furrows above described are about the best made available. In all cases heavy clods and big flakes will interfere with your work by letting the water through the ridges if too plenty.

Where the checks are to be permanent, as for alfalfa, they may be made well. enough on many soils with the ridger. More care must of course be taken, and generally they should be rolled or dragged down into shape. A very effective scraper called the "Fresno scraper" is used in the large alfalfa fields for making these ridges, and does very perfect and rapid work. But for ordinary fields it is not necessary to buy any machinery.

When made with a ridger at each junction of a ridge with another crossing it

keep you jumping too rapidly to keep it from breaking away. If you have too many for it to fill at a time then you will do too much leaning on the hoe, and, as you generally have to hire help at this time if working much ground, you want to save time as much as anything. You will soon find the right medium by trial. Also when and in how many places to break a check so as to let the water quickly into the next one, and also how to build the lowest place in a ridge so that the water will flow out when you want it to and not before. No rules can be given for this work that are not subject to so many exceptions as to be almost worthless.

The time required to get the water over a ten-acre tract with a head of two cubic feet a second or one hundred miners' inches under four-inch pressure will vary

from six to fifteen hours, according to the nature of the soil and the necessity of rushing the water over it rapidly, and also according to the number of the checks and the freedom of passage for the water through them and out of them. With larger heads you can do it in less time but will need more help, and vice versa. But slow flooding is generally bad, especially where the water stands deep, and generally all that remains in a check after doing its work is a detriment and no longer a benefit.

run

Sometimes checks are fed from a main at the upper side exactly as in orchard work with fine furrows. And where the checks are numerous and small this is often best, dividing the head so as to take the checks in blocks or tiers. Often it may be better to have the ditch through the center feeding to right and left. The trouble in such case is to empty the checks fast enough without wasting the water. Where one feeds another there is little waste. The ditch must in all cases be high enough to ensure rapid and certain feed of water.

The time required to soak the ground will also vary greatly with the nature of the soil. If the checks are so made that they do not break and let out more water than you intend, the soil will be well soaked in two or three hours, and often less time after the check is covered on the bottom. If it takes much longer than this, it is pretty strong evidence that the texture of the soil is so close that fine furrows would do better for all orchard work. For in such case you are quite certain to be troubled with the soil baking too much and making it difficult to cultivate and keep the soil open with cultivation. There is also danger of scalding tender stuff in hot weather.

As the upper checks feed the lower ones and are thus full for a longer time in a long series, one would suppose that the upper side of the field will be much wetter than the lower. The same would be expected from fine furrow work. But in general no difference can be seen if the work has been well done. And it is not difficult to arrange the breaking of the checks in such way that the water will remain longer in those at the lower side. But you need not at first trouble yourself with such points, but concentrate all your talents on getting the water over the whole

as quickly as possible without having it stand too deep or too long in any one place. When once you have mastered this you will find all the rest easy enough. And if you have laid out the slope right and made the checks with care, and have plenty of help to handle the rush of water when it comes, you will find no trouble even with this.

PROTECT THE TREES AND VEGETABLES.

Flooding may be used for all sorts of vegetation. But where possible, the stalk or stem of everything should be protected from contact with the water. In the case of trees it is easy to leave a little mound about the trunk so that there is no excuse for the water touching it. But with many vegetables and small tender stuff it is generally impossible to do this at any reasonable cost. If the plants cannot in such case be set up on a little ridge above the water it should be spread over the whole in a thin sheet with the greatest speed possible. And if possible it should be done in the afternoon or evening so that the sun cannot strike the stem until it and the ground around it are comparatively dry. Plants differ much in the ability to endure the baking of the ground around the stem and the scalding of the stem from having the hot sun strike it while Young melons, for instance, are quickly hurt, while young radishes seem unaffected. As a rule the evil is exaggerated by many. Not much harm will be done anything if the water is not allowed to stay around it too long, or too hot a sun allowed to strike the stem too soon after the water is taken off. In cool,

wet.

cloudy weather there is little danger. As it would take you years to find out just what different things will bear in this way it is best not to risk it, but keep the water away wherever it does not cost too much in labor or money to do so.

water until old enough to shade the ground and become tough enough to endure considerable baking and scalding. The soil should be well soaked before plowing even if it takes two or more floodings to do it. Then, when in condition, it should be so well plowed and harrowed that it will retain moisture and remain mellow. Then your stuff can grow two or even three months without more irrigation and in many places will make a crop of grain without any more. But to flood it just after it is up is always to hurt it, and often to ruin most of the stand, however good it may be.

The great problem in flooding is how to make a number of checks feed each other without having the water stand too long in each, or having it run so fast through the upper ones as to cut or otherwise damage anything in it, and at the same time to use up the whole head in the series so as to have little or none to waste at the lower end.

If checks do not feed each other, then you have the expense of more laterals and gates, and more care in watching each check so as to get in just enough water to soak away quickly, and no more. If you have to have a waste ditch at the lower end to empty the check completely and see that it is done, then you might as well have one feed another at once. If you can run just the right amount into a check at once and be sure that it will soak away quickly enough to avoid scalding, or such puddling as is sure to result in bad bak

ing, even if no sun strikes it, then, everything else being equal, it is best not to have one check feed another. But it often costs more in time and labor.

Suppose, then, you are feeding a line. of ten checks, one from the other. You want to have each soak an average of two inches in depth. If you let twenty inches in depth into the first one, with the view of letting it all out when it has settled down two inches, you may press down and puddle the soil too much in a very short time. Many soils, such as a fine granite soil, will rarely stand this, and in some such a depth of water will by puddling stop the soaking instead of hastening it.

You must then start with less water and run in more after you have cut the check to let it into the next one. But this involves the danger of keeping deep water too long in the first one, or else cutting the soil or injuring vegetation by running the stream over the bottom of it after it is emptied. And whichever way you try to avoid these troubles you may find yourself at the end with a large amount of waste on hand which should have gone in the ground. For you want to learn at the outset that waste hardly ever pays.

There is no royal road out of these difficulties, because each case must be decided on its own peculiar state of facts. But if you bear in mind the main principles you will soon find your way out of the woods with a little patience.

(To be continued.)

MANY of the large and important irri

gation systems of the world derive their supply of water from storage or impounding reservoirs.

A storage reservoir is the artificial lake bed or basin formed by closing the outlet or outlets to a valley or canyon. After the outlets are closed by means of artificial barriers called dams, water entering the valley is retained in the basin and accumulates, thus forming an artificial lake from which water can be drawn as desired. The object of storage reservoirs therefore becomes apparent, the water entering the basin at times of the year when it is not needed for irrigation, being conserved to be drawn off and used at other times when irrigation is practiced.

A storage reservoir for developing a water supply for irrigation purposes is expedient and useful only in regions where such a large proportion of the precipitation takes place during the proportion of the year, when no irrigation is practiced, as to render the natural water supply inadequate for the purpose of irrigating when irrigation is necessary.

There are certain requirements making a storage reservoir practicable, or at times even possible. These we will now enumerate and proceed to discuss in the natural order. They are as follows:

(1.) A suitable valley or basin.
(2.) A favorable dam site.
(3.) An adequate water-shed.
(4.) Proximity to irrigable lands.

It is always necessary that these requirements be all combined in such a degree as not to have the failure of an enterprise due to the absence of either one of them. At the same time it is not to be expected that they are all to be found present in a perfect state, nor even in a relative state of perfection for that matter.

The first and most necessary essential to constitute a valley or basin suitable for storage purposes is sufficient area. As will be seen later on the cost of building dams is always great so that it is necessary to have a considerable area which can be

flooded in order to make an undertaking of water storage profitable.

Of course no fixed area can be stated as a minimum for the reason that the figure must correspond to the amount of investment required for dams. Extreme cases are sometimes encountered when small tracts of only 300 or 400 acres can be profitably utilized as storage reservoirs. This is only the case, however, when the other requirements are developed in such a marked degree as to render the cost of constructing a dam very small and the average depth of water nearly if not quite equal to the height of the dam. The locality also tends to influence the question of whether a reservoir site of limited area can be profitably improved or not. The value of water varies so much in different localities that an enterprise, which would prove profitable in one place, might possess no value at all in another locality.

Next to sufficient area the most important requirement in a reservoir site is that the slope or pitch of the land included in it be light, uniform and gradual. Abrupt descent toward the dam site or steep side slopes from the middle of a valley toward either side often render it unfit for a reservoir site although it be of very large area. In order to make the flooding of a considerable area possible, where the slope is abrupt, a very high dam must be constructed, and the cost of dams increases so rapidly, in proportion to their height, as to condemn such propositions from a financial point of view.

The value of water for irrigation purposes in the particular locality in question is also an important factor to be carefully considered as well in this connection as has already been suggested in connection with the question of area. In localities where water is very valuable a grade of seventy-five feet per mile in the reservoir site may not be objectionable, while in other localities where water is cheap a grade of twenty-five feet per mile may be sufficient to condemn a storage project.

Should the soil in a proposed reservoir

site be of such a loose and porous character as to not be capable of retaining water, but such as would allow it to sink and escape too readily from the reservoir, that would be a fatal objection. In all cases under consideration, thorough examinations should be made to determine the condition in this particular.

Another matter of importance is the liability of the reservoir to fill up with materials having a specific gravity greater than water. Such materials are usually brought down from above by heavy floods, and the checking of the current when the water charged with them reaches the reservoir causes them to settle. This objection can sometimes be overcome by intercepting the materials before they reach the reservoir site or by sluicing them out after they are in. The former method is practicable when the materials are coarse, provided that a suitable place can be found in which to intercept them, and the latter when they consist of fine sand or soil and an opportunity exists for constructing scour or sluice gates for removing them. Materials having a less specific gravity than water cause no difficulty as they will float on the surface and escape over the waste weir.

REQUIREMENTS FOR A DAM SITE.

The conditions which make a site desirable for the construction of a dam are a narrow passage to be closed, a reasonable depth to material suitable for a foundation, good opportunity for draining the foundation, and proximity of suitable materials for constructing the dam.

All of these things materially influence the cost of a dam and in this way affect the feasibility of a project. Before any recommendation of a storage project is made, surveys and borings to determine the exact length of dam required, the depth to a foundation and the amount of water to be handled in draining the foundation should be completed. Then the class of materials required for a dam can be settled, the data already obtained enabling us to decide what type of dam to build. Next the point from which the materials for construction are to come ought to be ascertained, after which their cost can be accurately estimated.

Finally comes the estimate of the total cost of a dam based on all of the above by taking into account the contents of the foun

dation and section of the dam, the amount and cost of handling the material to be excavated for the foundation and the cost of cuts, tunnels or pumping water for drainage, together with the cost of finishings, gate tower, other equipments, superintendence and other incidental expenses.

SUFFICIENCY OF WATER-SHED.

In order to derive the greatest profit from a storage reservoir its tributary watershed should be capable of filling it at least once every year.

If the water-shed is limited so that the reservoir cannot with certainty be depended on to fill every year, a portion of the water has to be carried over each year, so as to ensure an ample supply for the ensuing year. In a case of this kind a large reservoir may lose a very considerable portion of its value, as the duty which it can perform will depend entirely upon how much of the reservoir will fill in years of minimum precipitation.

Thus it will appear that a large reservoir site and an easy dam site are not the only things to be sought, but that an ade quate water-shed for supplying it is of quite as much importance.

An examination of the water-shed tributary to a reservoir site is therefore a matter of great moment and in the following articles we will briefly discuss the points to be investigated and the lines upon which these investigations ought to be carried

out.

All of the territory draining into a reservoir site above the location of the dam is known as its tributary water-shed. To determine the area of this water-shed is the first matter of importance in investigating it.

Surveys from which the number of square miles or acres can be calculated should be made. These surveys should also be topographical in a measure, as the differences in elevation are important, so if the water-shed differs very much in elevation it should be classified accordingly. The exactness with which it is necessary to determine the area of a water-shed must be left entirely to the judgment of the engineer. Sometimes it may be so much larger or smaller than necessary that only a fair approximation of its size is required for making a report. In such cases it is usually sufficient to locate the principal points along the boundary lines of the