The bicycle has attained an economic position of vast importance. The roof garden ought to attain such a position, and it doubtless will soon--as we give it the opportunity it desires. The Arab or the Moor probably invented the roof garden in some long-gone centuries, and they are at this day inveterate roof gardeners. The American, surprisingly belated--for him, has but recently seized upon the idea, and its development here has been only partial. The possibilities of the roof garden are still unknown. Here is a vast city in which thousands of people in summer half stifle, cry out continually for air, fresher air. Just above their heads is what might be called a county of unoccupied land. It is not ridiculously small when compared with the area of New York county itself. But it is as lonely as a desert, this region of roofs. It is as untrodden as the corners of Arizona. Unless a man be a roof gardener, he knows practically nothing of this land. Down in the slums necessity forces a solution of problems. It drives the people to the roofs. An evening upon a tenement roof with the great golden march of the stars across the sky, and Johnnie gone for a pail of beer, is not so bad if you have never seen the mountains nor heard, to your heart, the slow, sad song of the pines. IN THE BROADWAY CARS. PANORAMA OF A DAY FROM THE DOWN-TOWN RUSH OF THE MORNING TO THE UNINTERRUPTED WHIRR OF THE CABLE AT NIGHT--THE MAN, AND THE WOMAN, AND THE CONDUCTOR. The cable cars come down Broadway as the waters come down at Lodore. Years ago Father Knickerbocker had convulsions when it was proposed to lay impious rails on his sacred thoroughfare. At the present day the cars, by force of column and numbers, almost dominate the great street, and the eye of even an old New Yorker is held by these long yellow monsters which prowl intently up and down, up and down, in a mystic search. In the grey of the morning they come out of the up-town, bearing janitors, porters, all that class which carries the keys to set alive the great down-town. Later, they shower clerks. Later still, they shower more clerks. And the thermometer which is attached to a conductor's temper is steadily rising, rising, and the blissful time arrives when everybody hangs to a strap and stands on his neighbour's toes. Ten o'clock comes, and the Broadway cars, as well as elevated cars, horse cars, and ferryboats innumerable, heave sighs of relief. They have filled lower New York with a vast army of men who will chase to and fro and amuse themselves until almost nightfall. The cable car's pulse drops to normal. But the conductor's pulse begins now to beat in split seconds. He has come to the crisis in his day's agony. He is now to be overwhelmed with feminine shoppers. They all are going to give him two-dollar bills to change. They all are going to threaten to report him. He passes his hand across his brow and curses his beard from black to grey and from grey to black.