The Gardener's Monthly, for May, tries to enlighten its readers on the most successful modes of planting shade trees in the city. It cautions us not to provide trees for our sidewalks except those that are easily moved, of a strong and vigorous growth, and proof against gas and worms. Trees possessing these confined qualities are indeed suitable for sidewalk planting, but The Gardener's Monthly fails to satisfy us in the trees thus qualified to grow rapid and strong, and resist the effects of gas and the action of worms. Gas, according to the theory of The Gardener's Monthly, kills thousands of street trees annually. Gas, we will agree, is destructive to vegetable life, if so confined as to be directly under the influence of gas. It is now a general belief among the more rational scientific men, that gas, once it leaves its confinement, makes its way swiftly, much rapider than smoke to the upper regious; that the continual emanation of gas from the various apparatuses mixes with the atmosphere while moving in swift currents upward, it is true.

Gas, as every school boy knows, is composed of aeriform fluid, with an impatient tendency to move upward, whether in a body combined or disseminated. Advocates of city trees would have us believe that gas in place of rising to a lofty destination, hovers close to the surface in a dewy vapor to be absorbed by everything vegetable that has pores to breathe.

If critical Tom would honor Cincinnati with his presence for a day or two, we would convince him double quick that gas should not be entirely blamed for the sickly appearances of shade trees on city sidewalks. We would show him to the gas works of a large institution in the center of this city, where a grove of various kinds of trees - trees that a sidewalk forester would deem unsuitable for the city, are growing and flourishing finely around the tanks, meters, retorts and purifiers of this gas structure.

Here, then, is a living monument for the man of science to study; absurd as it may seem, there are hundreds who will unhesitatingly vouch for the truth of this statement. Volumes of gas and smoke escape at the drawing and recharging of the retorts, a large portion of which passed between the leaves and branches without molesting them the least.

Flowers and shrubs thrive in the vicinity of the gas work, and we have seen a large group of the finer species of bedding plants perfecting their foliage and blossoms with health and vigor in' the distance of sixteen feet from the gas purifier.

In the suburbs of this city a gas apparatus is surrounded by cherry trees; escaping gas and smoke pass between the branches and leaves continually, yet these trees bear a heavy crop of fruit annually. The writer has time and again stood on the roof of this gas house and picked baskets full of rich and juicy cherries from the surrounding branches.

What is it then that we are to attribute that sickly, shriveled condition of trees in this city to? The pretending scientist will answer gas, while the more rational practicer will answer dirt, soot and dust, washed by drizzling rains into the interstices of the bark, stifling the pores and thereby depriving the trees of their breathing facilities. Why not economize a portion of the water so lavishly wasted in cleansing the pavement under those dirty trees? Why not direct the nozzle of the hose towards them? they are stifled and gasping for breath - let the water play with force against the bark, leaves and branches. This will animate new life, encourage growth, health and vigor, and help to dislodge any pests that are inclined to feed on the foliage.

The Gardener's Monthly enlightens us in following mode: Trees die for want of nourishment, being planted on sidewalks that have been graded up with coal ashes and other refuse, without sufficient soil being put to support them - they grow a little at first, and then gradually dwindle away.

We have seen trees grow luxuriantly in coal yards, where cart loads of coal dust could be shoveled off their roots. We can also affirm from practical experiences, that refuses of lime, mortar, saw dust, wood chips, shavings, etc., mixed in the grade with sand, ashes, muck, clay, street sweepings and other rubbishes when packed together under the pavement for a few years will rival the loam of the forest in maintaining the life and vitality of trees. Speaking from a practical standpoint, we can also confidently assert, that trees once taken root in these accumulated ingredients will dwindle away only when stricken with disease from dirt, dust and soot.

The Gardener's Monthly is inclined to condemn the Tulip poplar and Magnolia acuminata on account of their obstinacy to bear . a successful transplanting. Quite obstinate, we will agree, moreover, if laid on the sidewalk for half a day to bleach and then stuck in the ground close to the curb stone like lamps or hitching posts by some quack forester. The Gardener's Monthly further assures us that Lindens, Maples and Chestnuts are sure victims to insects, worms, etc,., and again adds, that Paper mulberry and Silver poplars should be discarded in consequence of their tendency to lean over and heave pavements.

Worms like to dwell among dirty things, you know. Use the hose; a strong stream of water will exterminate both pests and dirt, and float them safely into the sewer. The irregular tendency of the P. mulberry and S. poplar may be attributed to injudicious planting; as the trees grow old their roots cram the space between the curb stone and basement wall of the buildings. Street tree planters should learn how to sink the roots of trees below the lower edge of the curbstone, thus inducing the trees to extend their roots under the whole street.

'Tis now prudent for us to pause with a view to economize space, hoping The Horticulturist, as well as thousands of its readers, will agree that the first thing to be considered in this much agitated city tree question, is the cleansing of the trees.

Cincinnati, Ohio.