50 YEARS AGO
Marine biologists have been slow to recognize that the smaller phytoplankton elements which will pass through the finest nets are of great importance in the productivity of the oceans. In order to get some quantitative data on this subject for eastern Australia (lat. 33–34° S.), we have recently conducted experiments in which 44 gallons of sea-water were pumped into a drum and filtered through a phytoplankton net having 170 meshes per inch. The filtrate was collected and the particulate matter was spun out of 2-litre aliquots using a continuous centrifuge running at 13,000 rev./min... Both the net fraction and the centrifugate were examined microscopically, using the fluorescence of chlorophyll, to count the photosynthetic organisms... It has been found that the chlorophyll content of the centrifugate is 25–3,000 times as great as that of the net plankton, while the counts of organisms are 10–102 as high again... It is proposed to continue these studies over an annual plankton cycle, in an estuary, and in the open sea.
From Nature 3 March 1956.
100 YEARS AGO
A magnificent fireball was seen by many persons in the north of England on the evening of January 27 at 8h. 33m... Mr. H. Beckwith, at Hull, observed the meteor travelling horizontally between the “square” of Ursa Major and the Belt of Orion, while at Cheadle, Miss Blagg noted the path as just above ζ Leonis. Mr. R. Felton, at Patrington, estimated the brightness as quite equal to that of the full moon... The meteor gave a very brilliant flash near its end point, and the suddenness of its apparition startled many people... the height of the meteor was from about 59 to 45 miles over the North Sea immediately east of the Lincolnshire coast. The length of the observed path was approximately 42 miles, and probable velocity of the object 24 miles per second... In recent years fireballs have been very numerous this month, and especially at the epochs about January 9 to 13 and 24 to 29.
From Nature 1 March 1906.