VI. NATURAL HISTORY.--The Long-haired Pointer "Mylord." --With engraving. 7073 VII. HORTICULTURE, ETC.--Apple Tree Borers.--Protection against the same. 7074 Keffel's Germinating Apparatus.--With engraving. 7074 Millet.--Its Cultivation. 7074 VIII. MISCELLANEOUS.--Puerta del Sol, Madrid, Spain.--With engraving. 7063 Dust-free Spaces.--A lecture delivered by Dr. OLIVER J. LODGE before the Royal Dublin Society. 7067 * * * * * PUERTA DEL SOL, MADRID. Puerta del Sol, or Gate of the Sun, Madrid, is the most famous and favorite public square in the Spanish city of Madrid. It was the eastern portal of the old city. From this square radiate several of the finest streets, such as Alcala, one of the handsomest thoroughfares in the world, Mayor, Martera, Carretas, Geronimo. In our engraving the post office is seen on the right. Large and splendid buildings adorn the other sides, which embrace hotels, cafes, reading rooms, elegant stores, etc. From this square the street railway lines traverse the city in all directions. The population of the city is about 400,000. It contains many magnificent buildings. Our engraving is from _Illustrirte Zeitung_. [Illustration: THE PUERTA DEL SOL, MADRID, SPAIN (From a Photograph.)] * * * * * CONCRETE BUILDINGS FOR FARMS. Buildings made of concrete have never received the attention in this country that they deserve. They have the merit of being durable and fire-proof, and of not being liable to be blown down by violent winds. It is very easy to erect them in places where sand and gravel are near at hand and lime is comparatively cheap. Experiments made in England show that coal screenings may be employed to good advantage in the place of sand and gravel. Mr. Samuel Preston, of Mount Carroll, Ill., has a dwelling and several other buildings made of concrete and erected by himself. They were put up in 1851, and are in excellent condition. In _The Farmers' Review_ he gives the following directions for building concrete walls: