INTRODUCTION^. XXXVII 



Dr. Barnard, who, in addition to his knowledge of natural history, pos- 

 sesses mechanical ingenuity of a high order. After giving some time 

 to general observations in Mississippi and Alabama in the summer of 

 1880. he was called to §elma the latter part of August, and charged 

 with .mechanical work. It was there and early in September that 

 the cyclone-nozzle originated in our endeavors to contrive something that 

 would throw a spray from the ground up. The question was dis- 

 cussed between us as to whether water forced tangentially into a flat- 

 ened disc would rotate and issue from an outlet in a straight or in a 

 spreading jet. Dr. Barnard took the latter view, and a disc, improvised 

 by means of two watch crystals, so as to permit the motion of the liquid 

 to be seen, proved that he was correct. The size and form finally 

 adopted is the result of numberless subsequent experiments covering 

 a period of nearly two years. 



While we have always had a number of original ideas to carry out 

 and our direction of this work has been active, yet Dr. Barnard's as- 

 sistance was fertile from the first, and there is so much that has resulted 

 therefrom that the preparation of these chapters was finally assigned 

 to him, and he deserves much of the credit that attaches to them. It 

 was found expedient, on account of the large increase of matter, to de- 

 part from the general arrangement adopted in the first edition, which, 

 while it had the merit of simplicity, did not permit of so thorough a 

 classification. Much of the material in that first edition, is, however, 

 used verbatim in these chapters and such is placed in quotation marks, 

 so that any quoted passage without authority or credit may be under- 

 stood as being from that edition. 



In describing these various machines and contrivances, it has been the 

 endeavor to bring to the notice of the planter all that are worthy of 

 mention, and to point out their advantages and disadvantages and how 

 they may be used most economically and efi'ectively. The planter can 

 then judge for himself which he can most profitably adopt according 

 as his own circumstances dictate. Many of the older machines and 

 contrivances are thus mentioned or described (though now superseded 

 by improved ones) because they are of interest from a historical point of 

 view. 



Chapter XIY gives a short account of the history of the literature 

 on the Cotton Worm and closes with a bibliography up to and including 

 the year 1881. 



In Chapter XV are illustrated and described some of those insects 

 which either in the larva state, but more i)articularly in the imago state, 

 are liable to be confounded, and in fact have often been confounded, 

 with the true Cotton Worm. As the northern Army Worm [Leucania 

 unipuncta) in the imago state is, from its color and frequency, most 

 often thus mistaken in winter time, we have introduced a colored plate 

 of the species to facilitate comparison. 



Chapter XYI is devoted to the Boll Worm, and will be found to con- 



