470 Notes and Memoranda. 



view to discover the object of their erection. He finds the average slope of the 

 Great Pyramid, and of six others at Memphis, to be 52°, and the variation from 

 this mean to be slight. Moreover, the pyramids and funeral monuments which 

 surround them, are placed so as to correspond exactly with the four cardinal points. 

 Now it is observed when Sirius passes the meridian of Grizeh its rays strike upon the 

 south side of the Pyramid, and 3300 years B.C. they must have fallen perpen- 

 dicularly upon it, and thus, according to astrological speculation, must have exerted 

 their greatest influence. He therefore conjectures that the pyramids were built 

 so as to receive the most complete illumination from the brightest star in our 

 heavens, which was consecrated to Sothis, the celestial dog and judge of the 

 dead. The date of 3300 years B.C. corresponds with Bunsen's calculation, 

 according to which the pyramids were built in the reign of Cheops, in the 34th 

 century before our era, and it also coincides with the Arab tradition that they were 

 constructed three or four centuries before the Deluge, in the year 3716, before the 

 Hegira, 



Ozone produced BY Plants. — Mr. C. Kosman has communicated to the 

 French Academy a series of observations, from which he draws the following 

 conclusions : — 1. Plants evolve ozonized oxygen from their leaves and green parts. 

 2. They disengage during the day ozonized oxygen in a greater ponderable 

 quantity than exists in the circumambient air. 3. During the night the difference 

 between the ozone produced in the plants, and that contained in the air, becomes 

 nil in the case of isolated vegetation, but where the plants grow thickly and 

 vigorously, this ozone is more abundant than that of the air. 4. Plants in the 

 country evolve more ozone during the day than town plants. 5. From this cause 

 country air is more exhilarating than town air. 6. In the midst of towns, and 

 of a dense population, the night air exhibits more ozone than that of the day, but 

 in proportion as the animal population diminishes, and the vegetable kingdom 

 predominates, the diurnal ozone increases until it exceeds that of the night. 7. The 

 interior of the corollas of plants do not evolve ozone. 8. Inhabited rooms do not 

 usually contain ozonized oxygen. 



Oxygenized Water. — M. Chevreul finds that this preparation destroys 

 colours of an organic origin, just as chlorine does, but more slowly. 



Size oe Microscopic Printing and Writing. — Mr. Webb addresses us a 

 note, in which he says he has measured the first i in " shilling," as it appears in 

 one of the microscopic cards supplied to our readers, and he finds it "to 

 be approximately the -^^ X to'oo = "500W0 °f aa inch." The specimen which he 

 engraved for us was by no means intended to represent the limit of perfection to 

 which he has brought this curious art, but such as could be easily read with a 

 moderate power by persons of ordinary sight. He sends us the "Lord's 

 Prayer," beautifully printed from copper, in which he states the letters are 

 ttoo X itotj — 2T3oa o °f an i nc -h, and he observes in his note, " startling as the 

 above numbers appear at first sight, yet the letters are very large when compared 

 with those which have been cut upon glass, some of which are cnly the forty 

 millionth of an inch." He adds, " In your September number you mentioned 

 my chapter of St. John. That specimen has been measured by several gentlemen, 

 who all agree in stating it to be the -fa X sV> or y^ of an inch. The 4137 

 letters in that specimen, multiplied by 1054, give 4,360,398 letters to the square 

 inch, while the whole of the Bible and Testament are said to contain only 

 3,566,400 letters, thus showing that at the rate in which the chapter of St. John 

 is written, the whole 'Bible and Testament, and more than three-quarters of a 

 million ad ditional letters, would come into the square inch " Mr. Webb also calls 

 attention to the extreme minuteness of the particles of blacklead with which the 

 lines of the finest writing on glass are filled by the gentleman who mounts his 

 specimens. Their size, he says, would require at least ten figures to express it, 

 and such figures are probably only a tenth of the number l-equired to state the 

 dimensions of Dr. Faraday's ruby gold. 



Bolides. — On the 26th November, about 5 P.M., a large meteor was seen 

 described " as big as two fists," and lighting up a lane near Chiselhurst. On 

 the same date, but at 6 p.m., a gentleman near Broxbourne saw a large meteor 



