The engraving of the beautiful church we this week reproduce is from the excellent and elegant monthly, the Architectural Renew and American Builders' Journal, and for which we are indebted to the courtesy of its publishers, Messrs. Claxton Kemsen Haffelfinger,819 and 831 Market Street,Philadelphia. It was erected by the widow of the late Col. Samuel Colt, at Armsmear, near Hartford, Conneticut, in memory of her deceased husband and children,as a church for the use of armorers and their families, and others employed on the estate. It is a Gothic Church designed by Mr. Edward T. Potter, architect, and embraces a nave and aisles; chancel, with arrangements for a choral service; Sunday-school, opening out of the church as a transept; baptistry; organ-room and vestry; and a tower and spire. The walls are of Portland brown stone,relieved with dressings of Ohio stong. Around the semicircular apse of the sacrari-um, which terminates the chancel, is carried an arcade of thirteen lancet windows filled with stained-glass, bearing figures ot our Lord and the Twelve Apostles, after the design of Over-beck. The arcade is decorated, externally with alternate jwl-ished shafts of red and black granite, standing free, whose capitals are carved with olive foliage and the appropriate apostolic symbols. The church has an open-timbered roof, of polished chestnut, novel, but beautiful in design, illuminated with gold and vermilion. Rich borders with texts and other decorations in color, are introduced in the interior. T'he baptistry and organ room, on either side of the chancel open into it and into the church by arches. Those in the chancel are carried on polished red col-unms, with white marble capitals, carved with water lilies. The design of the font—suggested by Mrs. Colt, and being carried out by Mr. Mofiitt, sculptor—consists ot three children supporting a shell, executed in white marble; and is intended as a memorial. At the west end of the church is a largo memorial window, of elaborate design and beautiful coloring, which—as well as the other windows (all of which are filled with stained glass) —is by Mr. Sharp. A screen divides the Sunday-school from the church. It is made ol chestnut wood, like the wainscoting, pews, and fm-niture of the church, some of which is richly carved. The screen is filled with plate glass, and can be opened orclosed at pleasure, uniting or separating the church and Sunday-school. Similar but smaller screens are introduced in the arches of the organ room and baptistry. Among the carvings which adorn the exterior, perhaps the most interesting are those of the south porch, the armorers' porch as it is called. Under the symbol of the cross, and half concealed in fohage, are representations of the different parts of all the fabrics in making which the workmen's days are spent. Around the entrance arch is carved this text : "Whatsoever ye do, do all to the glory of God; " words which are, for those who placed them there, or those who read, at once an admonition and prayer. How much better such a monument than the costly piles often erected over the tombs of the once wealthy dead, whose only use is to point out the spot where lies a little human dust. The latter speaks only of death. The former speaks of a better and enduring life beyond the grave. ' Iron and Steel Crystals. Mr. Schott, of Ilsenberg, Saxony, says the Railway Times, has made many microscopical examinations of the structure of steel and iron. He maintains that " all crystals of iron are of the form of a double pyramid, the axis of which is variable, as compared with the size of the base. The crystals of the coarser kinds, as compared with those of the finest qualities of crystalline iron, are of about twice the hight. The more uniform the grain, the smaller the crystals, and the flatter the pyramids which form each single element, the better is the quality, the greater is the cohesive force, and the finer the surface of the iron. These pyramids become flatter as the proportion of carbon contained in the steel decreases. Consequently, in cast iron and ia the crudest kinds of hard steel the crystals approach more the cubical form, from which the octahedron properis derived, and the opposite extreme or wrought iron has its pyramids flattened down to parallel surfaces or leaves which in their arrangement produce what is called the fiber of the iron. The highest quality of steel has all its crystals in parallel positions, each crystal filling the interstices formed by the angular sides of its neighbors. The crystals stand with their axes in the direction of the pressure or iier-cussive force exerted upon them in working, and consequently the fracture shows the sides or sharp corners of the parallel crystals. In reality good steel shows, when examined under the microscope, large groups of fine crystals like the points of needles—all arranged in the same direction and parallel." Tlie Fire-Fly. This insect is not strictly speaking a fly, but a true beetle, belonging to the order Ooleoptera and the family Lampyrid. Everyone is familiar with the appearance of these beetles, as their soft glow which is ever and anon vanishing and reappearing, illumines the pleasant evenings of July and August. At a is represented the larva as it appears when full grown. It fives in the groxmd, where it feeds on other soft bodied insects. At times these fire-fly larv must subsist al most entirely on young earth-worms, forwe have found them abundantly in soil, on which no vegetation had grown for at least one year, and where in consequence there was scarcely another animal to be found besides these two—the fire-fly larva feeding upon the earth-worm, and the latter subsisting on the earth itself. Each segment of the larva has a horny brown plate above, with a straight white line running longitudinally through the middle, and another somewhat curved one, on each side. The sides are soft and rose-colored, and the spiracfes which are white, are placed on a somewhat elevated and nearly oval dark brown patch. On the under side it is of a cream color, with two brown spots in the center of each segment as shown enlarged at e. The head (magnified at /) is thoroughly retractile within the first segment, which is semicircular, and gradually narrowed in front. But the most characteristic feature is a retractile proleg, d (or hmppe mrwuseB the French have more graphically called it) at the extremity of the body,which not only assists in its locomotion, but serves to cleanse the head and fore part of the body from any impurities that may adhere to them after it has finished a meal. It is quite amusing to watch one, as it deftly curies its body and stretches this houppe fan-like over its head, and literally washes itself. When full grown, or during the latter part of June, it forms an oval cavity in the earth, tlirows off its larval skin, and becomes a pupa as represented at 6. In this stage it is white, with a tinge of crimson along the back and at the sides, and after a rest of about ten days, it throws off its skin once more and becomes a beetle like c. The light which is of a phosphorescent nature, is emitted from the tip of the underside of the abdomen, two of tho segments being of a sulphur-yellow color, in contrast with the rest, which are dark brown. The light is emitted both by the larva and pupa, though not so strongly as in the perfect insect. There are other species belonging to this family which inhabit North America, and which emit a light, and these are doubtless popularly known as fire-flies in their several districts. In some of them tho females are almost or quite wingless, with but very short wing cases, but in this species both sexes are winged, and have full-sized wing cases.—Entomolo-gist. Pastel)oard and Asplialte Kooflng, The Building News contains an account of an application of pasteboard in connection with asphalte as roofing material, recently tried in Copenhagen. It says this material satisfies all the reqjiirements of a substantial roofing, resisting effectually the influence of water, fire, heat, and cold. The article is cheap, and its use considerably lessens the cost of timber work; a roof covered with it having at the utmost only one third the weight of a tiled roof. It stands high with regard to safety from fire, the result of several public trials being that the Danish Insurance Companies, as well as the English and Gorman Companies, represented in Copenhagen, consent to insure goods stored in buildings roofed with the asphalte pasteboard r-t the premiums fixed for buildings with fire-proof roofing. Prize medals have been awarded to the manufacturers at Stockholm, Odense, and the Havre Maritime Exhibition of 18G8. The price of the material is low, 6s. Gd. per roll containing 7i yards, while the asphalte mastic with which the roof has to be coated when completed, is sold at 9s. 9d. per cwt., one hundred weight covering a surface of 5 square yards. The roofing material is most suitable for fiat roofs, having a fall of one inch and a half to four and a half inches per running foot; it may, however, also be used for roofs having a greater fall, the expense being in this case somewhat larger than by flat roofs, the laying on being more diflacult. The roof has to be first covered with dry boards three-quarters of an inch to one inch thick, and rather not above six inches broad; but if the boards are more than six inches broad, or if not sufficiently dry, they ought to be split once before being laid on, in order to keep them from warping, as also every board should be fastened with three nails at least on each of the rafters. The boards do not require to be rabbeted; only that end of the boards which, forming the eaves, extends beyond the wall, ought to be joined in the said manner. In case of boards three quarters of an inch thick being applied, the rafters should not be more than two feet from 53 each other, as the hoards else may he too elastic and not strong enough to support the weight of the workmen during the roofing, while the roof will not he perfectly substantial. The roofing may be done either from gable to gable, or from the eaves to the foot ridge, tlic first roll being laid with a bend of one inch beyond the roof and fastened with the flat-headed iron TOre nails supplied for that purpose. The second roll is laid one inch or one incli and a half over the first, and so on till the roof is covorcd. The joints and heads of the nails are then coated with the asphalt-mastic, and the seams thus coated are strewed with dry sand. Tlio -whole roof is then coated with the mastic and strev/ed with sand. Tliis coating, which is only to bo cfFectcd in dry weather, renders the roof perfectly water-tight, and it can then, if it bo desired, be painted or whitewashed.