September, 1913. 



KNOWLEDGE. 



349 



THE U.S. TORNADOES OF MARCH 23rd, 1913— In 

 connection with the system of low barometric pressure which 

 crossed the United States during the latter part of March, 

 severe local storms occurred in portions of Kansas, Nebraska, 

 Iowa, Illinois and Indiana. The tornado at Omaha, Nebraska, 

 on Easter Sunday, the 23rd, was most destructive. From the 

 account in the Monthly Weather Review it seems that 

 ninety-four persons were killed, as well as thirty-three horses, 

 four cows and five mules. At Terre Haute, Indiana, the 

 tornado was less than two minutes in traversing the city, 

 during which time about three hundred and thirty houses were 

 demolished or badly damaged, two hundred and fifty persons 

 injured and twenty-one lives lost. The Weather Bureau 

 official states : " I have talked with several persons who were 

 caught in the tornado. They saw the funnel-shaped cloud 

 touching the ground in places and house after house crumbled 

 as it passed over them. They say the roar was deafening, and 

 I was told by several persons that it could be heard for a mile. 

 Many freakish things resulted : chickens were defeathered, 

 the clothing was drawn off a bed through a fireplace and 

 thence up the chimney ; in one house the linoleum was raised 

 off the floor ; in another a baby was lifted out of its bed, 

 carried a square, and laid down without injury ; toothpicks 

 were driven into the hard wood of a sideboard on which they 

 were laid, and a splinter of wood was driven through a large 

 phonograph horn." 



ELECTRICAL STORM IN KANSAS, MARCH 23rd.— 

 During the greatly disturbed weather conditions referred to in 

 the preceding note, an unusually severe electrical storm 

 occurred in the three western tiers of Kansas counties on Easter 

 Sunday, March 23rd. From an account given by Mr. S. D. 

 Flora we learn that during this storm windmills, especially 

 steel mills mounted on wooden supports, became so charged 

 with static electricity than anybody touching them received a 

 distinct shock, and in some cases the shock was a severe one. 

 The observer at Tribune, Greely County, reported an instance 

 where sparks two or three inches long were drawn from a 

 wire running to a windmill. Telephone and telegraph wires 

 and wire fences also became charged sufficiently to give quite 

 noticeable shocks, and in Scott County, where the disturbance 

 seems to have been most severe, one case was reported where 

 a prairie fire was thought to have originated from electric 

 sparks caused by a break in a wire fence. The observer at 

 Scott City also reported that sparks passed from a person's 

 finger held near a horse's ear, and that the horse would shake 

 his head as though he felt the contact of the spark. These 

 electrical phenomena, which occurred during high south-west 

 to west winds, were generally experienced from early morning 

 until about sunset ; and during this time the air was filled with 

 dust and was very dry, with no precipitation during the storm, 

 though light rain fell in the north-western part of the State 

 early in the evening. 



THE VELO CLOUD.— Dr. Ford A. Carpenter in his 

 recently published book, " The Climate and Weather of San 

 Diego and California," gives the following account of the Velo 

 cloud which is such a characteristic feature in the climate of 

 St. Diego. " While the velo cloud is common to the Pacific 

 Coast generally, and has been observed as far north as the 

 Straits of Fuca, this cloud reaches its perfection over the 

 littoral region of Southern California. The velo cloud is the 

 chief characteristic of the summer climate of the San Diego 

 Bay region. And summer should be understood as covering 

 all the year excepting November, December, January and 

 February. These four months could easily be reckoned as 

 spring-time. The screening of this region from the sun's rays 

 is so thoroughly accomplished that, during a normal summer's 

 day, the sun breaks through the velo cloud about 10 o'clock, 

 the sky clearing shortly afterwards and remaining free from 

 clouds until about sunset. That the velo cloud is effective as 

 a sun-shield, it needs only to be stated that the average of all 

 the July maximum temperatures since weather observations 

 began shows a mean of about 78°. 



" The cause of the formation of the velo cloud and, 

 consequently, the cool summers of St. Diego, is, strange to 



say, found in the hot weather in the interior of California 

 and Arizona. It is a unique example of the aptness of the 

 proverb, ' It's an ill wind that blows nobody good.' The hot 

 weather in the interior produces an aerial eddy (the ' low ' of 

 the weather map), and the difference in atmospheric pressure 

 between the interior and the ocean results in giving San Diego 

 cool, uniform days and nights, free from extremes, or what is 

 really the summer temperature of the Pacific Ocean. The 

 velo cloud should therefore be incorporated in our local 

 vocabulary, and it should replace the misnomer ' high fog.' " 



VERIFICATION OF METEOROLOGICAL INSTRU- 

 MENTS. — Dr. C. Chree, in his Report of the Observatory 

 Department of the National Physical Laboratory, has given a 

 list of the instruments examined at the Kew Observatory 

 during the year 1912. The testing of barometers and hydro- 

 meters was transferred to Teddington in November, but 

 including these it is shown that the total number of instruments 

 — exclusive of watches and chronometers — examined during 

 the year was 40,324, an increase of 3,875 on the previous 

 year. The number of barometers and thermometers tested 

 was : — 



It is stated that the increase in the number of thermometers 

 tested is due in considerable measure to the introduction of 

 new regulations by the Home Office for cotton factories. 

 These factories are required by law to have dry and wet 

 bulb thermometers to show the hygrometric conditions 

 prevailing, and the new regulations required the introduction 

 of what was practically a new type of thermometer. 

 Thermometers of " other forms " are also much more 

 numerous than usual, owing partly to a specially large supply 

 of those of the type issued in connection with the chilled 

 meat trade. 



MICROSCOPY. 



By F.R.M.S. 



A NEW PHOTO-MICROGRAPHIC APPARATUS.— 

 Although one hesitates to apply the word " new " to any form 

 of mechanical contrivance nowadays, seeing that any 

 newness about such things partakes of the nature of a fresh 

 arrangement of old principles or ideas, yet I venture to say 

 that the subject of this note presents various conveniences 

 which the photo-micrographer has not been able to enjoy 

 hitherto. I have had this piece of apparatus in practical use 

 for some time, and strongly commend it on account of its 

 convenience, ease of working, and also its efficiency. 

 Figure 377 shows a general view of the apparatus. It is here 

 seen resting on a long narrow table which was especially 

 designed and made for this purpose. The table bed, which is 

 of solid oak rather more than an inch thick, is supported by one 

 pillar at each end. The pillars divide so that the table rests on 

 four feet with castors of the form used for billiard tables. Under 

 the table-bed are three hanging drawers " running through " 

 and so get-at-able equally well from either side of the table. 

 The apparatus can be dismembered and all parts, except the 

 long square base bar, stowed away in these three drawers. 

 The legs of the table are fixed to the table top by nuts and 

 bolts, so that it can be taken to pieces for travelling. 



The shoes, and so on, are all tapped with the same thread, 

 so that the various parts are interchangeable in position. 



The photographic part consists of a five and a half feet long 

 straight, solid, square steel bar or base, A. A. On this slide 

 a number of square-fitting shoes supporting the various parts. 

 These shoes slide quite freely, and may instantly be clamped in 

 any position along the bar by means of milled headed screws 

 at the lower angle. The lamp end of the bar has a one-legged 



