576 abstracts: engineering 



MYCOLOGY. — Aspergillus fumigatus, A. nidulans, A. terreus n. sp. 



and their allies. Charles Thom and Margaret B. Church. 



Amer. Journ. Bot. 5: 84-104, figs. 3. February, 1918. 

 After comparison of a large number of strains in culture, the authors 

 have grouped three series of them under two old and one new specific 

 name. Cultural reactions for A. fumigatus and A. nidulans are given. 

 An ascosporic form with the conidial morphology of A. fumigatus is 

 described together with three ascosporic strains with the conidial mor- 

 phology of A. nidulans and slight differences in size and markings of 

 ascospores. Aspergillus terreus, a cinnamon or avellaneous form 

 widely occurring in soil, is described. The constant occujTence of these 

 three groups of strains in soil cultures led t6 experiments which showed 

 these forms, together with five strains of A. flavus, A. clavalus, A. ory- 

 zae, Penicillium luteum, P. pinophilum, and three strains of the Citro- 

 myces section of Penicillium, to grow and fruit readily upon and in three 

 types of soil used in laboratory culture. Full citation of the original 

 literature of these species and types either confused with them or 

 presumptively related to them are given. 



C. T. 



ENGINEERING. — Ground connections for electrical systems. 0. S. 

 Peters. Bur. Stands. Tech. Paper No. 108. Pp. 224. 1918. 

 This paper contains the results of an investigation of methods of 

 grounding electrical systems for protective purposes, made with special 

 reference to the National Electrical Safety Code. The subject is taken 

 up under the following main topics: (1) Resistance of ground connec- 

 tion; (2) their uses and service conditions; (3) different forms of ground 

 connections and the electrical characteristics of each; (4) mechanical 

 construction; (5) inspection and testing; (6) fire hazard and interference 

 with service; (7) costs; (8) bases for specifications; and (9) field meas- 

 urements of the resistance of ground connections. The section on field 

 measurements is perhaps of greatest interest to practicing engineers, 

 and contains results of resistance measurements on types of ground con- 

 nections now in use in thirty-seven cities in different parts of the United 

 States. In comparatively few places is it possible to obtain adequate 

 protection from electrical dangers by means of grounds made with 

 electrodes of small extent, such as driven pipes, plates, and other de- 

 vices. To obtain protection which is continuous and reliable, it is nec- 

 essary to make use of water pipes or common ground wires which 

 connect plate grounds in parallel. O. S. P. 



