JUNE 18.] THE NEW ZEALAND GAZETTE. 2461

108. Describe a thrust bearing. Which of the
     surfaces wears? Why are there sometimes a number
     of oil-tubes for one thrust bearing?

109. What parts of a screw-shaft are generally
     covered with brass? Why is this necessary? About
     what thickness is the brass?

110. What is the stern-tube or screw-shaft pipe?
     Why is a pipe of such a length required? Of what
     is it made? How is it fixed at each end?

111. What is a lignum-vitae bearing? How is the
     wood fitted? Where is such a bearing generally
     used?

112. How is a screw propeller fixed on the shaft?
     What means are used to prevent its getting loose at
     sea?

113. Where are sluice-valves placed? What large
     sluice-valve is there in almost all screw-steamers?
     From what position should this valve be worked?
     Why so? What attention should it receive?

114. With a condensing-engine, what valves or
     cocks are on the skin of the ship, in the engine-room,
     and in the stoke-hole?

115. What are the necessary fittings of a marine
     boiler?

116. With a surface-condensing engine, what cocks
     or valves are opened some time before the engine is
     started so as to be ready for starting whenever the
     order is given?

117. What is a steam-jacket? What cocks are
     on it? In what engines are jackets most generally
     used? Do they require to be felted?

118. What parts of an engine or its fittings should
     be felted or otherwise protected from radiation?

119. What are the small cylinders sometimes
     fitted on the slide-valve casing-cover of vertical
     engines? Explain their action. To what are they
     connected by a pipe? Why so?

120. Name the principal pipes in connection with
     the engines and boilers of a steamer, and state to
     what the ends of these pipes are connected.

121. Through what cocks or valves, pipes, and
     chambers does the water pass on its way from the
     sea-inlet rose-plate to the water-space of the boiler
     with a jet condenser?

122. Through what cocks or valves, pipes, and
     chambers does the circulating water of a surface
     condenser pass?

123. Through what cocks or valves, pipes, and
     chambers does the steam pass from the boiler until
     it is in the form of water in the hot well?

124. Name the pieces of the engine through
     which the pressure of the steam is transmitted from
     the piston to the screw propeller. Name them in the
     order in which they act.

125. What is an air-vessel? How does it act?
     At what parts of an engine or of its fittings are air-
     vessels generally applied?

126. What is the construction of a mud-box?
     Where should mud-boxes be placed? Why are they
     necessary? How should the space be divided by
     the rose-plate, and why?

127. What is a trunk-engine? Why has it fallen
     into disuse?

128. What is an oscillating-engine? For what
     steamers are oscillating-engines generally adopted?
     Why? How is the steam conveyed to and from
     the slide-valve casing?

129. Of what parts does the valve-motion gear of
     an oscillating-engine consist?

130. For what have geared engines sometimes
     been used? Of what were the cogs of the large
     wheel made?

131. At what part of a screw-steamer is the pres-
     sure that propels it applied to the hull?

132. At what part of a paddle-steamer is the
     pressure that propels it applied to the hull?

133. About how much fuel per indicated horse-
     power per hour is required by modern steam-engines,
     common, compound, and triple expansion?

134. What is the explanation of the economy of
     the surface condenser?

135. What is the construction of a surface con-
     denser? Of what are its tubes made? How are
     they fixed? How are they kept tight? What is
     done with a split tube?

136. Where do surface condensers foul? How
     are they cleaned?

137. What non-conducting substances are em-
     ployed to prevent radiation, and how are they
     applied?

138. In the construction of smoke-box doors and
     of dry uptakes, what provision is made to lessen the
     amount of radiation?

139. How can the formation of black smoke be
     prevented? Describe smoke-preventing apparatus.

140. What is meant by "circulation" in a boiler,
     and what are the results of defective circulation?

141. What means are sometimes adopted to im-
     prove the circulation in a boiler?

142. By what arrangement is the circulation
     promoted in a "hay-stack" boiler?

143. Describe a ship's side air-pump discharge-
     valve. In what respects does it sometimes differ
     from a common stop-valve, and what attention
     does it require?

144. What is the construction of a feed escape-
     valve, to what is its discharge connected, and how is
     its loading regulated? Where should the escaping
     water flow?

145. When there is no feed escape-valve, what is
     the arrangement of the feed valves or cocks?

146. What is the measure of a horse-power?
     How is indicated horse-power ascertained?

147. Has "nominal horse-power" a fixed mean-
     ing? What is the use of this expression? What
     is generally taken as the measure of 1-horse power
     nominal?

148. What is "back pressure" in a cylinder?
     About how much is it in each of the cylinders in
     your last steamer? Is excessive cushioning ever
     a trouble under certain conditions in modern engines?
     Say when and why and in which cylinder this occurs.

149. What is meant by "speed of piston"?
     About how much is the speed of piston in modern
     marine engines?

150. What is "atmospheric pressure"? What
     is its average amount? What instrument tells this
     amount?

151. What is "gross pressure" or "absolute
     pressure"? What pressure is it that is shown by
     steam-gauge?

152. What is meant by "cutting off" steam?
     How is it done? What part of the valve regulates
     the cut-off?

153. What is a piston slide-valve? Describe its
     construction. Why are such frequently employed
     in place of the common slide-valve? Have they any
     advantages compared with a common slide-valve?
     If so, name them.

154. What fixes the time of closing the exhaust?
     After the exhaust is closed and before the port
     opens for steam, what becomes of the steam that is
     in the cylinder?

155. What is the "lead" of the valve? What
     is its object? About what amount is it?