404 SECTIONAL TRANSACTIONS.—E. 
of population into the mining and industrialareas. Bilingualism has advanced 
rapidly with the introduction of universal education, the need of specialised 
scientific knowledge in the industrial areas, contacts with external culture, 
the growth of modern transport and the economic demands of organised 
industry. The problem to-day is whether Welsh culture can be expressed 
satisfactorily through the medium of the English language without the loss 
of its essential characteristics. 
AFTERNOON. 
Baroness EBBA HULT DE GEER.—Biochronology (2.0). 
Biochronology is defined as time measuring from evidence afforded by 
any rhythmically stratified organic matter. Annual deposition whether 
in clay or wood, i.e. varve deposition, appears to derive its mechanism 
ultimately from the sun and should be a durable register both of time 
and solar effect. 
De Geer’s measurements of the melt-water clay varves give a chronology 
which covers a period of 15,000 years, but the record is more complete 
for the glacial than the post-glacial period, and the latter is perhaps more 
important in human studies. By his record of the clay varves of the 
Angerman Valley in North Sweden, Lidén fixed the length of the post- 
glacial period at about 8,700 years, and Prof. L. von Post’s study of the 
pollen record of peat bogs and of the evolution of our forests affords a rich 
and valuable content in the chronological frame. 
Prof. Douglass by his studies of the rings of the sequoia tree has 
established a time-scale of 3,200 years, and it is now possible to date historic 
dwellings such as those of the pueblos in Arizona by studying the rings of 
the yellow pine used in their construction, tying them on to rings of recent 
pines from the same region, and also comparing them with those of the 
sequoia. Far-distance comparisons with the sequoia record sent over by 
Douglass for the purpose are now being carried on at the Geo-chronologic 
Institute in Stockholm under the name Biochronology. 
Lidén’s graphs of clay varves match those of the sequoia rings. The 
striking coincidence of the curves leads us to accept the date of A.D. 1017 
for the formation of the most recent clay varves and to reduce the length 
of the post-glacial period to 8,640 years. Graphs of the rings of logs used 
in an old bulwark or water-fort in Lake Tingstade, Gotland, have been 
found also to match those of the sequoia in the fourth, fifth and sixth 
centuries A.D., and by using Douglass’s time-scale it is estimated that the 
logs of the main fort were cut in the year A.D. 450, and those of the palisades 
at various times from A.D. 450 to A.D. 585. There is a coincidence which 
cannot be ignored. 
Some object to the application to conditions in Sweden of a time-scale 
worked out on American data, especially when the scale is based on the 
examination of trees whose growth depends on so many factors which are 
all liable to differ locally. De Geer has shown that whatever seasonable or 
monthly variations may occur, there is a general close correspondence of 
the graphs of annual mean temperature in widely separated regions. The 
points of similarity and difference match those of the clay varves and tree 
rings of the same localities. We may therefore regard clay varves and 
tree rings as a kind of materialised climatic annual mean, and the sun as 
the ultimate source of climate. Variations in isolation from year to year 
are regarded as due to variations, often biennial, in the meteoritic dust 
occurring between the planets within our solar system. 
