INTRODUCTION. 11 
the summer of 1918 and the measurements and tabulation finished soon 
after. I wish gratefully to acknowledge the courtesy of the editors of 
the Astrophysical Journal and the Bulletin of the American Geograph- 
ical Society for permission to use illustrations and extracts from articles 
of mine which they have published. Plate 9 and figure 31 in the text 
are from the former journal. Thanks are also extended to Professor 
Ellsworth Huntington for the use of several text-figures which first 
appeared in my chapter of his work (1914).' 
TREES SUITABLE FOR CLIMATIC STUDY. 
During the course of this investigation the wood and growth of 
numerous species of trees have been examined with reference to their 
adaptability to the purposes herein described. The collections visited 
include several in London, especially one in the South Kensington 
Museum, fossils in the Jermyn Street Museum, the lumber-yards of 
Messrs. W. W. Howard Bros. & Company, tree sections and fossils 
in the geological museum at Berlin, fossils in the lignite beds of Grube 
Ilsa near Dresden, and fossils chiefly in Munich and Vienna. In 
Taste 1.—List of trees in the Jessup collection whose rings were counted. 
Approx- : 
‘ . Quality 
Scientific name. Common name. Locality. see, ee of ring 
‘A.D. sequence. 
Pinus torreyana..| Torrey pine...... San Diego, Cal..| 1790 JA Peete i Sls haa eels 
Pinus radiata. ...}| Monterey pine....| Monterey, Cal..| 1855 22 Years: 2. s |b asa vscusies 
Pinus monticola..} Western white pine.| Oregon......... 1641 TL eVOerss ln. pan ee ee 
Brickner. 
Pinus strobiformis| Mexican whitepine.| Southern  Ari- 1706 22 Yeats. cilia ss dhe 
zona. 
Pinus strobus....| White pine....... Nova Scotia....| 1740? | 22 years; | Fair. 
Brickner. 
Pinus teda...... Loblolly pine...... Florida......... PISS Io adu nid syle Un 'stlc va oc ee 
Pinus echinata...| Short-leaved pine.| Missouri........ SOOO) lees Wicd tools Papen 
Tsuga hetero- | Western hemlock..} Canada north- 1700 | Uncertain...|.......... 
phylla. west coast. 
Tsuga caroliniana | Carolina hemlock..} Carolina........ 1697 | Poor, 22 yr.;| Good. 
Brickner. 
Tsuga canadensis.} Canadian hemlock.| Nova Scotia....| 1525 11 years; | Good. 
Brickner. 
Pseudotsuga ma- | Bigcone fir........ Southern Cali- 1480? | 11 years....| Good 
crocarpa, fornia. 
Pseudotsuga mu- | Douglas fir........ Oregon......... 1315 11 years....| Good 
cronata. 
Picea sitchensis...| Tideland spruce...| Northwest coast | 1798 |............ Very good. 
Picea rubens..... Red spruce....... ING yes OOS if AEROS Rodis, « Scie dhe fs «cad Wieder 
Sequoia gigantea.| Bigtree........... California....... 550 Brickner Good. 
Taxodium dis- | Bald cypress...... Wloridas 5 <0 deck ROC beccoi cad en'sld fs asiiw ones 
tichum. 
Cupressus mac- | Macnab eypress...| Northern Cali- ROO ON ie ae 658 te Very good. 
nabiana. fornia. 
Toxylon pomifer- | Osage orange...... Southern Arkan-| 1765 |............ Fair. 
um. sas. 
Ulmus fulva...... Slippery elm...... Missouri........ 1770. | 20-years «...}.......6s00 
