"rain," "fair," etc., if required. It is 

 presumed that reference can be made to 

 a standard barometer for tlie purpose of 

 determining the points of the scale. Two 

 comparisons should be made on different 

 occasions, once when the stanrlard 

 instrument is very low, and once when 

 it gi\es a high reading. Say the two 

 readings are 27 and 31 ins. respectively. 

 Then the distance between the two 

 corresponding positions on the home- 

 made barometer may be provisionally 

 divided into 40 equal portions and 

 called tenths of an inch, the figures 

 being marked to correspond. But an 

 effort should be made to check as many 

 of these intermediate positions as pos- 

 sible by comparison with the standard 

 instrument. — H. J. Gr.w. 



Killing Vermin with Gas 



HVDROCYAXIC-ACID gas is one of 

 the most efficacious agents in rid- 

 ding households of such pests as bedbugs, 

 fleas, cockroaches, ants, clothes-moths, 

 etc. Rats and mice, when exposed to 

 its fumes, run out of their holes into the 

 open and die there. There is thus no 

 subsequent annoyance from dead rodents 

 in the walls and under flooring. 



Even when only one room of a house 

 is to be fumigated the entire house must 

 be vacated and so closed and marked 

 with signs that everyone is kept out. 

 The windows in such a house must be 

 equipped with ropes so that they can be 

 opened from the outside when the 

 fumigation is done. If the house is close 

 to another, especially if its windows are 

 below those in an adjoining house, care 

 must be taken to protect neighbors. 

 This is especially necessary in the case 

 of a house in a row, particularly if the 

 partitions separating houses are not 

 tight, or if its attic or roof air-space com- 

 municates with those in the neighboring 

 houses. For these reasons, in the case of 

 summer cottages at beaches, it is safest 

 and easiest to fumigate before the family 

 or neighbors have moved in, when there 

 is plenty of time to air the house com- 

 pletely after it has been treated. 



While hydrocyanic-acid gas is proba- 

 bly the most efficient means of ridding a 

 house of vermin, it is also one of the 

 most deadly poisons. Therefore, the 

 greatest care should be exercised in its use. 



Popular Science Monthly 



A Wallpaper Remover 



119 



THE difficulty and incon\enienre inci- 

 dent to the removing of old wall- 

 paper and the preparalif)n of the wall for 

 redecoration are reduced to a minimum 

 by the use of a new tool that gets at the 

 root of the trouble. It works under the 

 paper, or, rather between the paper and 

 the wall, softens up the paste or glue and 

 freely strips the paper from the wall. 



Every bit of wallpaper should be removed 

 before beginning the work of repapering 



It is particularly adaptable where 

 there are se\"eral layers of paper to be 

 removed, or for stripping oft' e.\tra hea\'y 

 or varnished paper. The usual way of 

 Hooding the walls with water or filling 

 the room with steam are not necessary. 

 The simple mechanical device illustrated 

 generates steam on the spot with a 

 gasoline burner and the steam is con- 

 trolled by a vaKe in the hand-piece 

 where it is driven behind the paf)er in a 

 thin sheet. 



