SEPTA'RIA are ovate flattened nodules of argillaceous limestone, internally divided into numerous angular fragments by reticulating fissures radiating from the eenter to the circumference, which are filled wish some mineral substance, as carbonate of lime or sulphate of barytes, that has been infiltrated subsequent to their formation. The fis sures have been produced by the cracking.of the nodule when drying. They are 1:,rgest and most numerous in the center, and gradually decrease outward, that the external crust had first become indurated, and so, preventing any alteration the size of the whole mass, produced wider rents as the interior contracted. The radiating fig ure. and the striking contrast between the dark body of argillaceous limestone and the more or less transparent sparry veins, when the nodule is cut and polished, Las caused them to be manufactured into small tables and similar objects. They are, however, most extensively employed in the manufacture of cement. As they are composed of clay, lime, and iron, they form a cement which hardens under, water, and which is known commercially as Roman cement, because of its properties being the same as a famous hydraulic cement made of ferruginous volcanic ash brought from Rome. Septaria occur
in layers in clay deposits, and are quarried for economical purposes in the clays of the London basin. Large numbers are also dredged up off Harwich, which have been washed out of the shore-cliffs by the waves. The nodules generally contain a scale, shell, plant, fruit, coprolite, or some other organic substance, forming the nucleus that has apparently excited the metamorphic action which withdrew from the surrounding clay the calcareous and ferruginous materials scattered through it, and aggregated them around itself.
SEPTEMBER (Lat. Reptern, seven) was the 7th month of the Roman calendar, but is September (Lat. Reptern, seven) was the 7th month of the Roman calendar, but is the 0th according to our reckoning, though we preserve the original name. 'Various Roman emperors, following the example of Augustus, who changed "Sextilis," the 6th month of the Roman calendar, into'" Augustus" (August), attempted to substitute other names for this month, hut the ancient appellation continued to hold its ground. The Saxons called it gerst-monath, or barley-month, because barley, their chief cereal crop, was generally harvested during this month. It has always contained 30 days.