Vol 6 Iss. 2

Alexander Yakovlevich Perna (1878 - 1916) was born into a family of the Estonian intellectuals. A. Ya. Pehrna received his secondary education at the 7th Petrograd Gymnasium. Upon completion of the gymnasium, he entered Petrograd University in the Natural Sciences Division of the Faculty of Physics and Mathematics, from which he graduated in 1902 with a first-degree diploma. He then entered the Mining Institute, from which he graduated first in his class in 1910. While still a student, he participated in detailed geological studies on the eastern slope of the Southern Urals. This work provided him with material for several geological and paleontological articles on the Upper Devonian and Lower Carboniferous deposits of the Urals (see the list of works in the article).

While examining the petrographic material I collected in 1914 during geological studies in the Middle Vitim Mountain Country, I encountered among the limestone specimens examples in which a well-preserved oolitic deposit could be observed under the microscope, only partially masked by subsequent recrystallization. The considerable interest presented by the discovery of oolitic formations among the metamorphic rocks of the Vitim Plateau prompted me to familiarize myself in more detail with oolitic structures using material where the primary structure was not be obscured by secondary alterations.

If we divide a cube by three mutually perpendicular central planes into eight small cubes, we obtain a periodic operation that we can continue infinitely in both directions. In this process, the volume of the cube decreases (or increases) by a factor of eight, that is, two cubed. But this period is very simply divided into three smaller periods with a decrease (or increase) in volume by a factor of two. In this periodicity, a special role is played by A) the centers of the faces of the original cube and B) the centers of the cubes of the lower period.

Alexander (Elmar) Yakovlevich Perna was born on December 6, 1878, into the family of a public school teacher in the Estland Governorate. He studied at the 7th Petrograd Gymnasium and, from his gymnasium years, showed a particular interest in natural science. Upon graduating from the gymnasium in 1898, Alexander Yakovlevich enrolled in the Natural Sciences Division of the Faculty of Physics and Mathematics at Petrograd University, where he was initially especially drawn to organic chemistry. After graduating from the University in 1902, he entered the Mining Institute. On December 3, 1916, he died of a heart condition in a Finnish boarding house. In the person of Alexander Yakovlevich, our homeland lost not only a talented young scientist who undoubtedly showed great promise, but also a man of exceptional high moral qualities and a distinctive and profound thinker and philosopher.

In the article "Results of the First Stage of an Experimental Investigation of the Structure of Crystals," the term *basic parallelohedron* denotes that smallest parallelohedron with marked arrangements of atoms within it, from which the entire system of atoms is derived by means of the symmetry elements of the bond. In the system of atoms, therefore, there are several different orientations of the basic parallelohedra with their atoms, namely according to the degree of symmetry of the bond (see the article).

Throughout the last year, A. Ya. Pehrna served as Chairman of the Geological Circle. This self-education Circle was founded in 1910 and had at one time been actively working, but when in 1914 many of its members joined the active army, the Circle's well-established life was interrupted for nearly a year and a half. Only A. Ya.'s exceptional energy and his remarkable personal charm succeeded in reviving the Circle and bringing it back to life in January of this year.

Direct experience shows that the phenomenon of crystallization is a highly complex one, in which various factors play a decisive role. Although, according to Steno's law, the angles between corresponding faces in crystals of the same substance are constant, the appearance of the forms that condition crystallization is far from being completely constant. At first glance, something even contrary seems to be the case. From one and the same substance, one can obtain crystals with a very limited number of pairs of faces, in exceptional cases not even reaching three, and one can also obtain crystals with a very rich combination. The forms that make up the combination also vary greatly in their development, and those very forms which in one case are predominant in terms of their size, in other cases recede into the background or are even completely suppressed by other forms.

Tikhon Semenovich Osennikov completed his secondary education at the Penza Realschule and was the only one from his family to enroll in a higher education institution — the Mining Institute — in 1911. He had only his graduation projects left to complete before finishing his studies at the Institute when his young life was so suddenly cut short. He died at the age of 23.

In establishing the structure, we were guided even earlier not by the complete sum of combinations that a given crystal exhibits, but only by a small number of the most important pairs of faces. In this respect, as we see, no change has occurred. Even now, we must first of all note these most important forms, but previously we calculated the density of these forms, since, after all, the sequence of faces by importance was still the basis. Now this calculation is no longer necessary, and the matter is significantly simplified, because it only remains to determine, based on these forms, which of the three belts these forms fall into.

A. A. Borisyak suggested that I study the Liassic fauna he and his colleagues had collected in the vicinity of Yalta and the village of Bodrak in Crimea. In the vicinity of Yalta, this fauna was noticed in the fencing of an estate. Careful searches eventually led to a small abandoned quarry, where a block of limestone containing the said fauna was found among shales. It was not possible to determine the relationship between the limestones and shales on site. The research provided undeniable paleontological evidence that part of the Crimean shale strata belongs to the Lias, and the villages of Bodrak and the vicinity of Yalta yielded the most abundant Liassic fauna.

The initial material was combustible shale collected during prospecting work by N. F. Pogrebov. After the distillation of illuminating gas, a tar remains, which served as the material for this study. During the distillation of this material in a water bath, crystalline, very thin plates of the distilled organic substance deposit in the tube, with inclusions of another substance having a significantly higher refraction and apparently capable of very good crystallization. This distillation was carried out by Mr. Valchis.

In the summer of 1914, geological investigations were carried out in the area of the Aleksandrovskaya Dacha (Perm Governorate), led by Professor N. N. Yakovlev of the Mining Institute. I worked in the eastern part of the dacha, and there I was able to observe the interesting geological phenomena that provided the material for this note. The most remarkable of all these phenomena in this locality should be considered the sinkholes (see the article). Among other interesting phenomena, caves can be noted. Of these, the most interesting in terms of size, shape, and origin are two. The first, the Vsevolodovskaya Cave, is located at the very endof the limestone cliffs, extending beneath them on the bank of the Chanva River. Initially, it has the appearance of a large niche, in the side of which there is a cleft that goes into the depths and stretches (together with the first niche) for 20 sazhens. Inside this cave there is a lake, gradually deepening towards the end of the cave. In the depths of the cave, approximately halfway, the cave walls are covered with stalactite deposits. The floor of the cave is littered with irregular blocks and fragments of limestone, which are also found under the water at the beginning of the lake.

One theorem states that the distance from the gnomonostereographic projection to the linear projection in a certain plane is equal to the distance from the latter to the vanishing point of the rays. The proof reduces to the fact that the vanishing point of the rays Z, the gnomonostereographic projection P, and the midpoint of the linear projection of the plane O constitute the vertices of an isosceles triangle, having the first two points at its base, and this, in turn, reduces to proving the equality of the angles at the base.

This work, which is my first work in the field of crystallography — a student work — encompasses substances of a random nature that were placed at my disposal from various laboratories. The particular feature of this work is that it applies, for the first time, the methods of computational crystallography set forth in the articles by Prof. E. S. Fedorov: "Fundamental Formulas of Spherical and Plane Tetragonometry" and "Calculation of the Symbol Numbers of a Complex" (Vol. IV, pp. 373 and 391, "Zapiski Gornogo Instituta"), with the designations for the faces whose coordinates were taken as the basis for calculation, as well as for the fundamental constants of the complex of faces, being the same as those used in the cited articles.

Issues of work and pressure during rolling, which are obviously related to one another, have long been the subject of research, both theoretical and experimental. The number of major experimental studies devoted to these issues is small. For my part, I shall dwell only on those conclusions of other researchers whose consideration is prompted by the course of my own investigation (see the article). The theoretical study by Codron was accompanied by laboratory experiments on the rolling of lead bars between rolls of small diameter. I shall discuss these experiments in some detail later, since they, above all, gave me the opportunity to verify the correctness of the theoretical formulas I derived.

On February 28, at the Mining Institute, on the initiative of a radical group, a student meeting took place with the participation of professors and employees of the Institute; a resolution was passed with the following content: "In view of the agreement reached between the Provisional Government and the Council of Workers' and Soldiers' Deputies on all current issues, the students of the Mining Institute condemn any actions not coordinated with them and call upon the country to support the Provisional Government and place all their forces at its disposal until the convening of the Constituent Assembly, which the students consider to be the true expression of the will of the country."