title: How can I append items to Observable
body: <p>How do I append items to <code>Observable</code>?</p>
  
  <p>This is some code:</p>
  
  <pre><code> this.logEntries = this.controllerService.getLog(this.controller.remoteID, this.skip, this.max);
  
          this.logEntries.subscribe(a =&gt; {
              this.allLogEntries.add(this.logEntries)
          });
  </code></pre>
  
  <p>and here is their declarations:</p>
  
  <pre><code> logEntries: Observable&lt;Log[]&gt;;
      allLogEntries: Observable&lt;Log[]&gt; = Observable.empty&lt;Log[]&gt;();
  </code></pre>
  
  <p>I want to append items to allLogEntries as they are being fetched from the web service. How do I do this?</p>