On subjective impressions or how to put numbers to visual illusions

This paper presents a simple theory to analyze some of the more common visual illusions. The reported mathematical model is able to give some numerical results concerning well known phenomena as the Zollner, Muller-Lyer or Wundt illusions. We present two different approaches, the first one related with the symmetrical operations present in each image and the second one concerning a proposed vector field related with the lines present at the image

The cardinal numbers : with an introductory chapter on numbers generally /

Mode of access: Internet.

The American cotton spinner and managers' and carders' guide : a practical treatise on cotton spinning : giving the dimensions and speed of machinery, draught and twist calculations, etc., with notices of recent improvements : together with rules and examples for making changes in the size and numbers of roving and yarn /

Cover title: American cotton-spinner.

Journal of a tour on the north west coast of America in the year 1829, containing a description of a part of Oregon, California and the north west coast and the numbers, manners and customs of the native tribes,

"No. 64 of 150 copies printed. Also 10 copies printed on Japan vellum."

The builder's complete assistant, or, A library of arts and sciences, absolutely necessary to be understood by builders and workmen in general : viz. I. Arithmetick, vulgar and decimal, in whole numbers and fractions. II. Geometry, lineal, superficial, and solid. III. Architecture, universal. IV. Mensuration. V. Plain trigonometry. VI. Surveying of land, &c. VII. Mechanick powers. VIII. Hydrostaticks : illustrated by above thirteen hundred examples of lines, superficies, solids, mouldings, pedestals, columns, pilasters, entablatures, pediments, imposts, block cornices, rustick quoins, frontispieces, arcades, porticos, &c. : proportioned by modules and minutes, according to Andrea Palladio, and by equal parts : likewise great varieties of trussed roofs, timber bridges, centerings, arches, groins, twisted rails, compartments, obelisks, vases, pedestals for bustos, sun-dials, fonts, &c. and methods for raising heavy bodies by the force of levers, pulleys, axes in peritrochio, screws, and wedges, as also water, by the common pump, crane, etc. : wherein the properties, and pressure of the air on water, &c. are explained : the whole exemplified by 77 large quarto copper-plates /

All of the numbered plates in the atlas are double plates, and thus are counted twice in the adjusted plate count.

Sunspot numbers, 1610-1985 : based on "The sunspot activity in the years 1610-1960" /

Mode of access: Internet.

Memoir on the theory of the partitions of numbers /

Mode of access: Internet.