Skeleton architecture was popular in Poland during numerous stylistic periods. In many regions of the country, a characteristic feature of the nineteenth century (and especially its second half) and the beginning of the twentieth century was a sudden development of this type of architecture. In contrast to previous periods, the buildings erected at the time were made of square-sawn timber with smaller cross-sections, which is the result of the progress of engineering know-how (static calculations, mechanical sawmills). The form and shape of the building were affected by numerous factors, the more important being the character of a given town or its district. Buildings raised in resort towns or villa districts differed from the ones built in the suburbs. A direct impact was exerted by the production of local sawmills and woodworking workshops, which produced ready-made and prefabricated elements. Up to this very day, the majority of the skeleton buildings raised in the discussed period is considered sub-standard and has not been conserved. Research on architectural detail is, as a rule, hampered since it is precisely detail which the first to be destroyed. An analysis of architecture and archival acts confirms that the size and shape of a building were influenced by factors mentioned in the introduction to the article. On the other hand, they did not exert an impact on the character of the applied detail. Further research will show precisely how many architectural details are of individual design, and how many were the outcome of compilations.
The second order nonlinear optical coefficient dsg of potassium hydrogen bis-trichloroacetate molecular crystal is theoretically predicted by the chemical bond method, which shows that optical responses of this crystal originate from the C-C1 bonds. The predicted value of d(36) is in agreement with the experimental observation.
Dielectric properties - linear (refractive indices) and nonlinear optical responses - of urea crystal are quantitatively calculated using static ab initio quantum chemistry calculations at the self-consistent field (SCF) level of theory. The polarizabili-ties and first hyperpolarizabilities of the urea molecule are used to calculate macroscopic susceptibilities of the urea crystal. The calculated values of the urea crystal can agree well with experimental data and other reports. The effect of hydrogen bonds on the susceptibilities of the urea crystal may be neglected. The present work provides us a useful way to deal with quantum chemistry calculations of such molecular crystals as urea.